Guessing on the GRE: the grand synthesis

2000-11-06 Thread Stephen Black

After considering all the activity on this one, I think I'll have
to nudge my position a bit closer to the opposition.

Concerning my objection to Marc Turner's post on being a "good
guesser" on the grounds that there's no such thing, I see now
that his problem for me wasn't faulty logic but ambiguous
phrasing. By "good guesser" he didn't mean someone who could beat
the odds but someone who, by chance alone, happened to do better
than what would be expected on average. I suggest "lucky guesser"
is a less confusing term for what he had in mind. And, contrary
to Karl Wuensch's recent post on the topic, "guessing" to me _is_
blind guessing, making a decision when one has absolutely no
information on which to base a choice.

I compliment Marc for his empirical approach to the issue. But
this is one case where collecting data isn't the way to go; logic
is. Here's my grand synthesis.  Remember, the aim of this
exercise is to provide test-taking advice for students: if you
absolutely don't know, should you guess or should you leave the
question out?

Suppose you are clueless. And suppose you are a student (but I
repeat myself). If you have absolutely no information on which to
base a choice, on average it makes no difference whether you
guess or skip the question. But, as Marc points out, that's only
in the long run, and sometimes your guessing will bring you more
joy, and sometimes less, purely by chance. So in individual
cases, a guessing strategy will sometimes help, sometimes hurt. 

So the advice to a student would be: If you have no basis
whatsoever for deciding among the five alternatives, guess if
you're a gamblin' man (or woman), or don't guess if you're a
cautious sort. But only the very poorest of students answering
the very best of questions will find him or herself in this
unhappy state of absolute cluelessness. More likely, the student
will be able to detect that at least one of the choices is less
than what it pretends to be.

Then, if you have even the slightest reason to reject even one
answer, Lady (or Lord) Luck will turn, ever so slightly, in your
favour, and you should certainly take a chance and guess at the
remaining choices.

I believe this brings me within shouting distance of Nancy
Melucci's position (hi, Nancy!), even if we don't exactly
correspond.

I hope but have my doubts that this will dispose of the issue.

-Stephen


Stephen Black, Ph.D.  tel: (819) 822-9600 ext 2470
Department of Psychology  fax: (819) 822-9661
Bishop's Universitye-mail: [EMAIL PROTECTED]
Lennoxville, QC   
J1M 1Z7  
Canada Department web page at http://www.ubishops.ca/ccc/div/soc/psy
   Check out TIPS listserv for teachers of psychology at:
   http://www.frostburg.edu/dept/psyc/southerly/tips/











Re: What is guessing?

2000-11-06 Thread Drnanjo
Listmembers -

Karl W wrote:

"And if this is what
Nancy's students understand "guessing" to mean, her telling them not to
guess on the SAT is very poor advice indeed!"  

I have noted and am offended by your patronizing tone. I have been doing this work for four years and I am very explicit about what kind of guessing I mean.

We (the tutors) tell them not to WILD guess - not to guess when they have no clue and have not eliminated any of the answer choices. We coach them on all kinds of elimination strategies, in order to help them raise their chances of picking correctly.  We also (Dr. Timmerman) help them review and learn all kinds of relevant content in order to become more knowledgeable people as well as better test takers. Standardized test taking is a skill that can be learned, and that appears to control the destiny of many students (or understandably appears to do so.) Many students, both worthy and perhaps not so have figured out that taking a test that has a limited predictive value in determining their success in college, will be a major hurdle. I don't see the moral issue in teaching them to do better on the test, using every legitimate strategy available.

Nancy Melucci


balancing frequency of correct answer options

2000-11-06 Thread Karl L. Wuensch

Those of you who try to "balance" the number of times 'a'  'b'  'c' and 'd'
are the correct answer options are just giving students another way to
"guess" the correct answer without knowing the material.  You should use a
random process to determine in which position the correct answer will
appear.  Do that and you might be surprised how often you get "runs" of
three or four correct answers in the same position -- we greatly
underestimate the probability of such runs in a truly random process.

Marc has been telling us that with truly random guessing it may be true that
on average the score will not be affected, but some will be lower (and some
higher).  But that is also true when the "guessing" is not random, even when
it follows having with certainty eliminated one of the alternatives.  If
nothing else, this current discussion has illustrated well that humans,
including Ph.D. holding psychologists, do not understand probability very
well.

++ Karl L. Wuensch, Department of Psychology, East Carolina University,
Greenville NC 27858-4353 Voice: 252-328-4102 Fax: 252-328-6283
[EMAIL PROTECTED] http://core.ecu.edu/psyc/wuenschk/klw.htm




What is guessing?

2000-11-06 Thread Karl L. Wuensch

My dictionary says "to judge or form an opinion from things that make
something probable but fall short of sufficient evidence."  I think this
matches what most people mean by "guessing" -- it is not a blind guess, they
have a hunch about it, but are not certain about it.  And if this is what
Nancy's students understand "guessing" to mean, her telling them not to
guess on the SAT is very poor advice indeed!  As Kalat and other have
demonstrated, "guessing" is not usually blind.  For example, there are a
number of strategies that examinees can use to get better than chance
performance even when they have no knowlege of the tested material -- for
example, always choosing the longest answer option (Kalat showed that this
strategy works well with the poorly constructed items in typical intro psych
test banks -- I always take care to avoid writing MC questions where this
strategy would pay off)

++ Karl L. Wuensch, Department of Psychology, East Carolina University,
Greenville NC 27858-4353 Voice: 252-328-4102 Fax: 252-328-6283
[EMAIL PROTECTED] http://core.ecu.edu/psyc/wuenschk/klw.htm




Re: Responsibility for missed lectures

2000-11-06 Thread Karl L. Wuensch

I suspect that some students do find it easier to miss class when they
know that my extensive notes are available on the web -- but that does not
bother me.  If the students can learn the material from my notes without
attending class, then I am satisfied.  But the serious students attend
whenever they can, because they know that in class they get the benefit of
hearing the interesting exchanges among class members (including me) and
they also get to hear my jokes that are too off-color to post on the web ;-)
Apparently most of my students actually enjoy attending my classes -- so
much so that their (and my peers') evaluation of my teaching has led to my
being given this year the highest teaching award in the University of North
Carolina system.  My head has grown two hat sizes since that event.  My
wallet grew too (a very nice stipend was included), but that did not last
long.

++ Karl L. Wuensch, Department of Psychology, East Carolina University,
Greenville NC 27858-4353 Voice: 252-328-4102 Fax: 252-328-6283
[EMAIL PROTECTED] http://core.ecu.edu/psyc/wuenschk/klw.htm
- Original Message -
> Karl wrote:
> All of my lecture notes are in Word files, so I simply convert them to
> web
> pages and post them where the students can get them if they miss class
> or if
> they were in class but would like to review my notes.
>
> Karl,
> I used to do this also, but then became concerned that students were
> just using these in lieu of attending class.  (My notes are pretty
> complete.)  Did you find this happened?  How did you handle it?
> Marcia
>
> Marcia J. McKinley-Pace, J.D., Ph.D.
> Assistant Professor of Psychology
> Mount St. Mary's College
> Emmitsburg, MD  21727
> (301) 447-4282
> [EMAIL PROTECTED]
>




Re: Night vision (Student question)

2000-11-06 Thread Karl L. Wuensch




Lots of possibilities -- distribution/density of rods, 
level of and rate of regeneration of rhodopsin (possibly related to diet -- eat 
carrots), clarity of any tissue through which light must pass on way to 
retina.  Or, maybe the brother and husband are just better guessers on the 
SAT.  ;-)  What most people describe as guessing yields 
better performance than would be expected by truely random 
guessing, and this applies to perceptual phenomena too (signal detection theory 
and all that). 

  - Original Message - 
  From: 
  [EMAIL PROTECTED] 
  
  To: [EMAIL PROTECTED] 
  Sent: Monday, November 06, 2000 6:15 
  AM
  Subject: Night vision (Student 
  question)
  Folks, Are there any explanations for 
  variations in the acuity of night vision from person to person (other than 
  owning night vision goggles)?   



Re: Faces: This message is not about guessing on the GRE

2000-11-06 Thread Molly Straight

They also have a full-color hard copy catalog which you can order by calling
1 800 962 1141. I am a retailer, in addition to my other positions, and have
found that is it usually far easier to call and get catalog than deal with
web sites problems and ordering from the web. I have discovered many great
wholesale suppliers through the web, but then order their catalogs.
Molly Straight, MA
Adjunct Lecturer of Psychology
Alderson-Broaddus College
Philippi, WV
- Original Message -
From: "Stephen Black" <[EMAIL PROTECTED]>
To: "TIPS" <[EMAIL PROTECTED]>
Sent: Sunday, November 05, 2000 9:14 PM
Subject: Faces: This message is not about guessing on the GRE


> Not too long ago, I plaintively complained about my inability to
> find an inexpensive source of faces expressing emotions. Marcia
> McKinley-Pace came to my rescue with a suggestion about getting a
> poster from a teacher supply store.
>
> She's now provided me with specific information, which I'm happy
> to pass on to the rest of you.  The emotion posters can be
> purchased from:
>
> ChildsWork/ChildsPlay at http://www.childswork.com/
>
> where they can be viewed and ordered on-line, at prices ranging
> from $11 to $19 US.
>
> The site is a bit tricky to navigate. I went through
> media-->posters--->emotions posters. They also may have a mix-up
> involving their Spanish poster.
>
> If you go through topic-->emotions--->emotions posters you get to
> a slightly different page with fewer choices (this drove Marcia
> and me crazy until we figured it out).
>
> Also don't forget to scroll down to see them all.
>
> The illustrations aren't too clear, but are clear enough to see
> that they're quite charming. So if you don't need them as
> experimental stimuli, you might want one for your wall. And I'm
> not getting a commission for saying that.
>
> Thanks, Marcia.
>
> Stephen
>
> 
> Stephen Black, Ph.D.  tel: (819) 822-9600 ext 2470
> Department of Psychology  fax: (819) 822-9661
> Bishop's Universitye-mail: [EMAIL PROTECTED]
> Lennoxville, QC
> J1M 1Z7
> Canada Department web page at http://www.ubishops.ca/ccc/div/soc/psy
>Check out TIPS listserv for teachers of psychology at:
>http://www.frostburg.edu/dept/psyc/southerly/tips/
> 
>
>
>




RE: The madness continues: the guess mess

2000-11-06 Thread Timmerman, Thomas

I haven't followed this whole thread, but has anyone mentioned
the possibility that getting a higher score may not necessarily
be a good goal? The purpose of the test is to determine how
much a person knows about a content area. If the person guesses
and gets it correct, their score incorrectly indicates that 
they know more than they do. If "guessing success" is normally
distributed (as is beginning to emerge in Marc's small sample), 
the "lucky guessers" will end up with higher scores
than the "unlucky guessers" of similar ability. If these scores
are used for admissions decisions, and the tests are valid predictors
of grad school performance, the "lucky guessers" will be in over their
heads and the "unlucky guessers" will not get into better
programs that match their abilities. 

Maybe guessing success isn't distributed normally, but the bottom-
line question is: Why do we want to help students get the highest 
score instead of the score that best reflects their ability?

TT

Thomas A. Timmerman, Ph.D.
Assistant Professor
Psychology Department
Austin Peay State University
Clarksville, TN 37044
931-221-1248
[EMAIL PROTECTED]




Re: The madness continues: the guess mess

2000-11-06 Thread jim clark

Hi

I think what is not being emphasized enough in this discussion is
that probabilities are expected values for an infinite
population; they do not apply to the outcome on any one occasion
or even on some finite set of occasions.  If someone guesses (in
the pure sense), then they will either be lucky, unlucky, or
neither on each occasion, depending on the fates (i.e., chance).  
That is, they might get a higher score, a lower score, or the
same score as if they had not guessed.  But the overall
expectation is of a result producing the same score by either
guessing or not guessing (depending on the penalty exacted for
guessing).  Perhaps whether or not one guesses should be
determined by how much of a risk-taker one is?  Do you want to
chance a lower score in order to have a chance at a higher score?

Best wishes
Jim


James M. Clark  (204) 786-9757
Department of Psychology(204) 774-4134 Fax
University of Winnipeg  4L05D
Winnipeg, Manitoba  R3B 2E9 [EMAIL PROTECTED]
CANADA  http://www.uwinnipeg.ca/~clark





Re: The madness continues: the guess mess

2000-11-06 Thread G. Marc Turner

At 07:06 AM 11/6/00 -0800, Diana Kyle wrote:
>E's = gain of points.  It is possible
>ETS structures answers to use each letter the same number of times?  If so,
>then consistent letter guessing
>is not an issue.   If not, then the probability of one letter being used
>more frequently in answers is
>important.   How many of us create exams with equal use of all answer
>letters?

When I use multiple choice items, I do try to balance the letters. BUT,
this means balanced over the entire test. So, it is possible that on any
subset of 5 items the alternatives would not be evenly distributed.

- Marc
G. Marc Turner, MEd
Lecturer & Head of Computer Operations
Department of Psychology
Southwest Texas State University
San Marcos, TX  78666
phone: (512)245-2526
email: [EMAIL PROTECTED]



Re: The madness continues: the guess mess

2000-11-06 Thread G. Marc Turner

As a follow up to my last post, I did ask students in my class to randomly
guess at 5 items with 5 possible answers to each. Here are the results:

5 right - 0
4 right - 0
3 right - 0
2 right - 4
1 right - 14
0 right - 9

So, those that guessed correctly on 2 items would have received +.5 (2
right - 1.5 for wrong answers). Those who got 1 item correct would have
broken even (0 points). Those that missed all 5 would have lost 1.25
points. So, as I believed, it is possible that some people would have been
hurt by guessing.

Admittedly a small sample, but if anything it points out that random
guessing doesn't ALWAYS help and can in fact hurt a person's score.

- Marc

PS- TEACHING RELEVANCE! I was able to tie the above data collection in with
a discussion of different ways of knowing and how we can turn to empirical
methods to examine questions. I didn't do this until after I collected the
data though... 
G. Marc Turner, MEd
Lecturer & Head of Computer Operations
Department of Psychology
Southwest Texas State University
San Marcos, TX  78666
phone: (512)245-2526
email: [EMAIL PROTECTED]



Re: lab exam

2000-11-06 Thread Carla Grayson

Dawn,

I taught a 1 semester hands-on lab in which we started with a review of basic
stats. I put together a simple user-friendly stat review handout. While my
students completed a take-home exam, I think an open-book stats exam with the
right support materials could be a good option. My theory is that after your
intro stat class life is an open-book stat exam. By and large, the exam was a
success experience for everybody.

Carla Grayson


Dawn Blasko wrote:

excepted: "For the second exam, I told the students that they would have

> a portion of the exam (I'm thinking 20%) in which they would demonstrate
> their understanding of design and statistics in the lab in very small
> groups.  Then I would ask them to upload
> a data set to spss, run the appropriate analyses (2-way anova) , print it
> and interpret the print out (what effects were significant) what followup
> tests to do.
>




Re: The madness continues: the guess mess

2000-11-06 Thread G. Marc Turner

At 09:40 AM 11/6/00 -0600, Mike Scoles wrote:
>Perhaps I am too trusting, but I've got to "guess" that the folks at ETS are
>not amateurs at test construction.   Favoring some distractors, either by
>placement of the correct answer or content of the distractors, is something
>that is avoided.

So, you are saying that for items it would be possible to eliminate some
distractors? If this is the case, then the guessing is not totally random
which is a very important point. Namely, if someone's odds of guessing the
correct answer improve because the eliminate one or two of the distractors,
then guessing is more likely to help. My argument is that with true random
guessing, it could hurt someone's score. An example would be that a student
has 1 minute left to answer the last 5 questions. Rather than reading and
answering 1 question should they guess at all 5 remaining items without
even reading the question or distractors.

- Marc
G. Marc Turner, MEd
Lecturer & Head of Computer Operations
Department of Psychology
Southwest Texas State University
San Marcos, TX  78666
phone: (512)245-2526
email: [EMAIL PROTECTED]



Re: moral dilemma?

2000-11-06 Thread Sharon Carnahan

I think this idea, about stressing students, is a bit mean.  It also violates
the bond of trust between teachers and students.  Look at it this way:  Would
it pass an IRB?  What was the pedagogocal benefit, and did it outweight the
cost?  Or did it just enable the teacher to engage in a bit of enjoyment of
power?

A similar protrayal of the use of power:  Several years ago, I chanced to
give a major test on St. Patrick's Day.  As I am Irish myself, I joked that I
would give 2 bonus points to anyone wearing all green to the test, and then I
forgot I'd said that.  On entering the classroom on the 17th I notoced that
something was jarringly different.  With a shock I realized that the WHOLE
ROOM was a sea of green.  I called my fellow profs in for a look!


Karen K Block wrote:

> Dear TIPsters,
> I love this antic, but take pause that it may be ethically
> questionable.  Could you help me decide?
> My student, intending to teach the topic of "stress", used an
> interesting activity.  She had, at the outset of her course told the
> students what the ground rules were:  so many tests, required
> participation, no pop quizzes, etc.  On the day allocated to"stress", she
> entered the classroom, and in a commandeering way told the students
> ..."Today we are having a little quiz""get out one half sheet of
> paper, please"  Faces dropping, paper tearing, students looking perplexed
> and a little unbelieving and a lot betrayed.  She used the moment well."
> I am going to dictate the quiz question.  Please write it down carefully
> and then we will have ten minutes to answer.  Thank you, and I look
> forward to reading your answer."
> "Now, she said, Listen Up"  (Silence prevailed and tension
> mounted).  She then spoke the quiz question slowly, very slowly, word by
> word, ostensibly so students could write down the question.  She said,
> slowly and deliberately, so they could take word for word dictation.
> "There..is...noquiz."  Of
> course there was collective relief.  And then she could relate their
> experience and feelings to "stress."
> Now I thought this was rather cool and wish I had thought of it.
> But then I realized deception was involved.  One of my more conservative
> students said,...Suppose one of her students had a heart problem!..And so
> I wondered what everyone here thinks inasmuch as this is a thoughtful
> bunch re:   what one actually says to students and how one interacts with
> them under the testiest of conditions at times.
> When I took her a bit to task, she averred that this was not her
> idea and she had read it in some TIPS-approved publication.  Then I
> thought perhaps my thinking was just too IRB reactionary and her teaching
> behavior was justified given the instructional point.
> This is clearly an issue needing collective wisdom.  Thanking you
> in advance for any true light you might shed on this matter.  KB




Re: The madness continues: the guess mess

2000-11-06 Thread Jeffrey Nagelbush

Although I have no trouble with the logic that says that guessing can't 
hurt, the assumption is that, if you do not know the answer, guessing will 
be random with respect to the correct answers.  However, it has been my 
experience that it is not that difficult to create questions for which one 
incorrect answer is much more likely to be chosen by those who do not "know" 
the correct answer.  Many standardized tests I have seen make use of comon 
errors in their distractor items.  If the Psych test does this, then 
guessing would not necessarily be the best option, since I assume most 
guessers will make what appears to them a "best" guess, rather than a random 
choice.  I really do not know if this applies to the test in question, does 
anyone else?

Jeff Nagelbush
[EMAIL PROTECTED]
Ferris State University



_
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moral dilemma?

2000-11-06 Thread David G Thomas/psych/cas/Okstate

To All:

One perspective on this question is that of Institutional Review Boards.
Our IRB at Oklahoma State U (on which I sit) evaluates proposals and their
risks by asking "Will the subjects encounter the possibility of stress or
psychological, social, physical, or legal risks that are greater than those
ordinarily encountered in daily life?" By this metric, I would say that
your student's demo did not carry risk greater than described in this
question.

Another aspect of this issue is the implied question of whether we as
instructors are obligated to minimize the stress that we put on students.
To this I would answer "No."

David G. Thomas, Ph.D.
Professor and Associate Head
Department of Psychology
Oklahoma State University
(405) 744-7078
[EMAIL PROTECTED]
- Forwarded by David G Thomas/psych/cas/Okstate on 11/06/00 09:46 AM
-
  
Karen K Block 
cc: (bcc: David G
 Thomas/psych/cas/Okstate)
11/03/00 Subject: moral dilemma?  
05:12 PM  
  
  



Dear TIPsters,
   I love this antic, but take pause that it may be ethically
questionable.  Could you help me decide?
   My student, intending to teach the topic of "stress", used an
interesting activity.  She had, at the outset of her course told the
students what the ground rules were:  so many tests, required
participation, no pop quizzes, etc.  On the day allocated to"stress", she
entered the classroom, and in a commandeering way told the students
..."Today we are having a little quiz""get out one half sheet of
paper, please"  Faces dropping, paper tearing, students looking perplexed
and a little unbelieving and a lot betrayed.  She used the moment well."
I am going to dictate the quiz question.  Please write it down carefully
and then we will have ten minutes to answer.  Thank you, and I look
forward to reading your answer."
   "Now, she said, Listen Up"  (Silence prevailed and tension
mounted).  She then spoke the quiz question slowly, very slowly, word by
word, ostensibly so students could write down the question.  She said,
slowly and deliberately, so they could take word for word dictation.
"There..is...noquiz."  Of
course there was collective relief.  And then she could relate their
experience and feelings to "stress."
   Now I thought this was rather cool and wish I had thought of it.
But then I realized deception was involved.  One of my more conservative
students said,...Suppose one of her students had a heart problem!..And so
I wondered what everyone here thinks inasmuch as this is a thoughtful
bunch re:   what one actually says to students and how one interacts with
them under the testiest of conditions at times.
   When I took her a bit to task, she averred that this was not her
idea and she had read it in some TIPS-approved publication.  Then I
thought perhaps my thinking was just too IRB reactionary and her teaching
behavior was justified given the instructional point.
   This is clearly an issue needing collective wisdom.  Thanking
you
in advance for any true light you might shed on this matter.  KB








Re: The madness continues: the guess mess

2000-11-06 Thread Mike Scoles

Perhaps I am too trusting, but I've got to "guess" that the folks at ETS are
not amateurs at test construction.   Favoring some distractors, either by
placement of the correct answer or content of the distractors, is something
that is avoided.

I cast my vote for Stephen's position.

 "G. Marc Turner" wrote:

> Lucky for us, this is something we can test (no voting required)... Have
> your students take out a sheet of paper and randomly guess the answers to 5
> non-existent questions. Each question has a possible answer of a, b, c, d,
> or e. Since we want them to truly guess randomly, we will not actually give
> them questions... we just want them to randomly give us the responses.
>
> Here is the key to use to grade the responses: C E D E D
>
> Now, grade the quizes... if ANY student fails to get at least 1 correct,
> the claim that it will NEVER hurt a person's score is false. At this point
> we know that Steven's claim does not have support from the data. If you
> continue scoring for everyone, you can figure out if my claim of getting 1
> correct, ON AVERAGE has support or not.
>
> Until we have actual data collected on this, I don't see much point in
> guessing as to the benefits or costs of guessing...

--
* http://www.coe.uca.edu/psych/scoles/index.html 
* Mike Scoles   *[EMAIL PROTECTED]  *
* Department of Psychology  *voice: (501) 450-5418  *
* University of Central Arkansas*fax:   (501) 450-5424  *
* Conway, AR72035-0001  *   *
*





Re: The madness continues: the guess mess

2000-11-06 Thread Diana Kyle


Just curious and just getting my coffee fix today.  What is the probability
our probability data are
representative?  Haha  Seriously now, many students believe if they are
going to guess an answer -
they should guess the same letter consistently throughout the examination.
This strategy should be
considered when considering guessing advantage.  Using Marc's data
collection exercise for example,
consistent A's or B's guessed = loss of points, C's = break even - D's or
E's = gain of points.  It is possible
ETS structures answers to use each letter the same number of times?  If so,
then consistent letter guessing
is not an issue.   If not, then the probability of one letter being used
more frequently in answers is
important.   How many of us create exams with equal use of all answer
letters?

My apologies if this has been discussed earlier.   Have a great day,
Diana

Diana J. Kyle, M.A.
Psychology Department
Fullerton, College

Office:  714-992-7166

We are what we repeatedly do. Excellence, then, is not an act, but a habit.-
Aristotle

The height of your accomplishments will equal the depth of your convictions.
   --William F. Scolavino


- Original Message -
From: G. Marc Turner <[EMAIL PROTECTED]>
To: TIPS <[EMAIL PROTECTED]>
Sent: Monday, November 06, 2000 5:36 AM
Subject: Re: The madness continues: the guess mess


> Steven is claiming that given 5 questions, with 5 answer alternatives
each,
> that all students will get at least 1 item correct by random guessing in
> ALL situations. This 1 item correct is what is needed when guessing at 5
> items to "break even" with a 1/4 point deduction for wrong answers.
>
> The claim I'm making is that given the same situation, students will get 1
> item correct ON AVERAGE. This means that, although most students will get
> the statistical 1 item correct, others will get more than 1 item correct
> and some will get less than one item correct. I do not agree that EVERYONE
> will get at least 1 item correct, only some will get this score. My
> understanding of probability is that it works ON AVERAGE, not in isolated
> cases. So, most students will break even, or even benefit, from guessing,
> but some portion of students will actually lower their score by guessing
> because they fail to get the 1 item correct.
>
> Lucky for us, this is something we can test (no voting required)... Have
> your students take out a sheet of paper and randomly guess the answers to
5
> non-existent questions. Each question has a possible answer of a, b, c, d,
> or e. Since we want them to truly guess randomly, we will not actually
give
> them questions... we just want them to randomly give us the responses.
>
> Here is the key to use to grade the responses: C E D E D
>
> Now, grade the quizes... if ANY student fails to get at least 1 correct,
> the claim that it will NEVER hurt a person's score is false. At this point
> we know that Steven's claim does not have support from the data. If you
> continue scoring for everyone, you can figure out if my claim of getting 1
> correct, ON AVERAGE has support or not.
>
> Until we have actual data collected on this, I don't see much point in
> guessing as to the benefits or costs of guessing...
>
> - Marc
>
> G. Marc Turner, MEd
> Lecturer & Head of Computer Operations
> Department of Psychology
> Southwest Texas State University
> San Marcos, TX  78666
> phone: (512)245-2526
> email: [EMAIL PROTECTED]
>




Night vision (Student question)

2000-11-06 Thread Claudia Stanny

Nancy Melucci asks:
> 
>Are there any explanations for variations in the acuity of night vision?

Visual sensitivity under low light conditions depends on several factors,
all of which might vary among individuals.

Dark adaptation (recovery of sensitivity following exposure to bright
light) depends on the speed with which the visual pigment rhodopsin is
regenerated in the rods.  Rhodopsin is formed from vitamin A (which is why
severe deficiencies of vitamin A produce deficits in night vision).  I
don't know whether individual differences in vitamin A would be manifested
as differences in quality of night vision - it generally takes a severe
deficit to show up as impaired night vision.  Any one know whether there
are differences in the speed of the regeneration process?

Several other factors might vary enough between individuals to create
differences in quality of night vision:  

Clarity of the cornea (people with cataracts will have worse night vision),
the lens, or of the viteous humor will determine how much light actually
stimulates the retina.  Less light transmitted, less to reach the retina to
be detected.

The size of the pupil when it is fully dilated might vary - the bigger the
opening, the more light the eye can gather.  Animals that have excellent
night vision (like owls) have large eyes and pupils that are capable of
great dilation.  

As we age, we accumulate pigments in the foveal region of the retina (which
also reduce our sensitivity to blue light) and these will filter out light
and affect vision under low-light conditions.  (This has been suggested as
the reason why little old ladies like those blue rinses - to them their
hair looks white, without them their hair might have a dingy, yellowed cast.)

Two other possibilities that are far more speculative:

Are there large enough individual differences in amount of convergence
among receptors in the periphery to produce differences in sensitivity?

There are some variations in the chemical composition of the photopigments
for color vision and these have slightly different sensitivity contours
(thus, there are different varieties of red-green anomolous color vision,
depending on which variant of the red/green photopigment the person has).
I suppose it is possible that there might also be variants in rhodopsin,
but I don't know of any research on that.

Claudia Stanny





Claudia J. Stanny, Ph.D.e-mail: [EMAIL PROTECTED]
Department of PsychologyPhone:  (850) 474 - 3163
University of West Florida  FAX:(850) 857 - 6060
Pensacola, FL  32514 - 5751 

Web:http://www.uwf.edu/psych/stanny.html



RE: Personality test for counselors [reposted]

2000-11-06 Thread Claudia Stanny

[The initial post seems to have been lost in cyberspace.  I apologize in
advance for the repetition if it reappears.]

I would like to broaden this thread a bit by posing several related
questions.  UWF has a Master's program in counseling psychology, places
students in supervised practica, and requires an internship experience in a
counseling setting as part of the degree requirements.  The questions about
screening students for psychopathology raise several important issues:

1.  Programs have an ethical and legal obligation to protect the community
from harm that might occur from placing a student in a practicum or
internship setting when the student is not prepared to function in these
environments either in terms of academic preparedness, quality of social
skill, and/or presence of  psychological dysfunction.  What is the best way
to go about evaluating students in a program to ensure that the community
has been duly protected?  Would it be appropriate to include such an
evaluation during the admission process?  If so, how can this be done
reliably?  (Our program eventually disbanded attempts at admission
interviews because the faculty did not believe these were serving their
intended purpose.  We now rely on extensive, term-by-term evaluation of
students in the program (on all the dimensions noted above) and may decline
practicum or internship placements if students don't seem ready.  Except
for course grades, this evaluation is done subjectively.)

2.  A colleague noted that requiring students to undergo therapy as part of
their training raises several difficult issues.  These include:  Who pays
for this therapy and/or determines who conducts the therapy?  If the
faculty act as therapists, problems of dual relations arise (should a
practicum or internship supervisor be in the business of conducting therapy
with his/her supervisee?).  If referals are made to external therapists,
problems of confidentiality arise (which will ultimately undermine the
usefulness of requiring therapy as a means of protecting the community from
harm) as well as other issues such as determining when "enough" therapy has
taken place.  

I have lots of questions and no good answers.  What do other programs of
this type do?

Claudia Stanny





Claudia J. Stanny, Ph.D.e-mail: [EMAIL PROTECTED]
Department of PsychologyPhone:  (850) 474 - 3163
University of West Florida  FAX:(850) 857 - 6060
Pensacola, FL  32514 - 5751 

Web:http://www.uwf.edu/psych/stanny.html



Re: Night vision (Student question)

2000-11-06 Thread Deborah Briihl

What I have read is the opposite - Males appear to have better visual
acuity under photopic conditions, while females have lower absolute
thresholds under scotopic - and can be seen in childhood. Females also
may dark adapt faster. There are other gender differences as well related
to acuity. I'm pulling this information from:
Coren, Ward, & Enns (1994) Sensation and Perception (4th ed.)

At 06:15 AM 11/6/00 -0500, [EMAIL PROTECTED] wrote:
Folks, 

Are there any explanations for variations in the acuity of night vision
from 
person to person (other than owning night vision goggles)?  


A student  asked what the explanation would be, according to her,
her brother 
and husband see better in the dark than she does . I also wonder since
this 
is a subjective and ancedotal account, if night vision has been studied
with 
this in mind (finding out who might have better than average night vision
and 
what neuroanatomical or neurochemical conditions would make this so.)


Thanks for any help you can give me. 


Nancy Melucci 
Los Angeles Harbor College 
Deb

Dr. Deborah S. Briihl
Dept. of Psychology and Counseling
Valdosta State University
Valdosta, GA 31698
(229) 333-5994
[EMAIL PROTECTED]

Well I know these voices must be my soul...
Rhyme and Reason - DMB




Re: Night vision (Student question)

2000-11-06 Thread Sue Frantz

Nancy Melucci wrote:

> Are there any explanations for variations in the acuity of night
> vision from
> person to person (other than owning night vision goggles)?

See: http://web.utk.edu/~wverplan/biblio10.html for the full article, by
William S. Verplanck from University of Tennessee, Knoxville.

*
"Night Blindness and Nyctalopia.

"Some persons report consistent difficulties in seeing at night, even
when they are fully dark-adapted. They cannot detect objects
readily visible to others and show both confusion and slow recovery
after brief exposure to relatively bright light sources.
Maneuvering in dimly illuminated spaces and driving or flying at night
present serious problems to these individuals. The
presence of such a history, whether the disturbance in sight is of
recent appearance or long-standing, is usually taken as prima
facie evidence of night blindness.

"However, a sharp distinction must be made between night blindness as
indicated by such reported difficulties and nyctalopia,
or true night blindness, which may be diagnosed only on the basis of an
accurate measurement of retinal sensitivity. Many, if not
most, of those individuals who report difficulty in seeing at night
prove to be psychoneurotic. Many who have unusually
insensitive retinas, on the other hand, do not report special
difficulties in seeing at night, either because they assume that others
have the same difficulties, or because they fail to note them in out
well-illuminated urban culture, which offers few situations in
which intact rod function is required. To establish the presence of
nyctalopia, it is essential to use an instrument of established
validity for the measurement of retinal sensitivity.

"Incidence of Nyctalopia.--No definitive data on the occurrence of
nyctalopia in the population are available, since
measurements have never been made on a representative sample of the
population. From the studies which have been made of
selected groups (e.g. school children, service men), it is known that
the normal population will include a small percentage of
persons of low visual sensitivity whose performance will be as poor as
or poorer than that of many individuals whose nyctalopia
is associated with disease or degenerative processes. About 2 per cent
of the Navy men were disqualified for night duties as
"night blind" on this basis. Those so disqualified seldom if ever showed
symptoms other than a relatively high absolute terminal
threshold, and their reduced sensitivity must be taken as the
consequence of the normal variability in the density in the retinal
rods and the efficiency of the process whereby rhodopsin, the visual
purple, is regenerated.

"The incidence of nyctalopia as part of a distinct clinical pattern is
not well understood. It has been observed frequently in several
diseases, and may appear in certain unusual conditions such as:

"(1) Idiopathic Nyctalopia.--Idiopathic nyctalopia is an hereditary
absence of rod function, which has been traced through
several generations of certain families. Although typically it appears
alone, it may be associated with color blindness and myopia.
There is no effective treatment.

"(2) Oguchi's Disease.--This rare hereditary syndrome, first reported in
Japan and later observed in Europe, has its primary
symptom nyctalopia with marked contraction of the visual field under low
levels of illumination. Ophthalmoscopic examination
shows a remarkably gray appearance of this fundus which disappears with
dark-adaptation. Day vision is not affected. No
treatment as proved of value.

"(3) Retinitis Pigmentosa.--Nyctalopia is the first and invariable
symptom of retinitis pigmentosa. In the early stages of the
disease, dark adaptation takes place, but at a retarded rate. As the
disease advances, rod function is progressively lost, and the
absolute terminal threshold is elevated. Diagnosis of retinitis
pigmentosa is based upon ophthalmoscopic examination.

"(4) Glaucoma.--Early impairment and progressive loss of rod sensitivity
is observed in glaucoma.

"(5) Retinitis Punctata Albescens.--The earliest symptom of this disease
is the complete absence of rod function. Often
nyctalopia is the only symptom associated with the altered state of the
retina.

"(6) Other syndromes of the Visual System.--Nyctalopia has been observed
as one symptom of each of the following
pathologic conditions: myopia, disseminated chorioretinitis, pregnancy,
nicotine poisoning, the Lawrence-Moon-Biedl
syndrome, gyrate atrophy of the choroid and retina, choroideremia and
atrophy of the optic nerve. Nyctalopia may be simulated
by opacities of the ocular media.

"(7) Overexposure to Sunlight.--Mild transient nyctalopia may appear in
persons who have been overexposed to bright
sunlight for several days. It will disappear within a few days if the
persons will protect their eyes from the sun wither by
remaining indoors or by the use of dark sun glasses.

"(8) Avitaminotic Nyctalopia.--Epidemics of night blindness hav

Re: The madness continues: the guess mess

2000-11-06 Thread G. Marc Turner

Steven is claiming that given 5 questions, with 5 answer alternatives each,
that all students will get at least 1 item correct by random guessing in
ALL situations. This 1 item correct is what is needed when guessing at 5
items to "break even" with a 1/4 point deduction for wrong answers.

The claim I'm making is that given the same situation, students will get 1
item correct ON AVERAGE. This means that, although most students will get
the statistical 1 item correct, others will get more than 1 item correct
and some will get less than one item correct. I do not agree that EVERYONE
will get at least 1 item correct, only some will get this score. My
understanding of probability is that it works ON AVERAGE, not in isolated
cases. So, most students will break even, or even benefit, from guessing,
but some portion of students will actually lower their score by guessing
because they fail to get the 1 item correct.

Lucky for us, this is something we can test (no voting required)... Have
your students take out a sheet of paper and randomly guess the answers to 5
non-existent questions. Each question has a possible answer of a, b, c, d,
or e. Since we want them to truly guess randomly, we will not actually give
them questions... we just want them to randomly give us the responses.

Here is the key to use to grade the responses: C E D E D

Now, grade the quizes... if ANY student fails to get at least 1 correct,
the claim that it will NEVER hurt a person's score is false. At this point
we know that Steven's claim does not have support from the data. If you
continue scoring for everyone, you can figure out if my claim of getting 1
correct, ON AVERAGE has support or not. 

Until we have actual data collected on this, I don't see much point in
guessing as to the benefits or costs of guessing...

- Marc

G. Marc Turner, MEd
Lecturer & Head of Computer Operations
Department of Psychology
Southwest Texas State University
San Marcos, TX  78666
phone: (512)245-2526
email: [EMAIL PROTECTED]



lab exam

2000-11-06 Thread Dawn Blasko

Hi everyone,

I teach a 2-semester 8 credit research methods core. In the first class we 
learn research methods, review the stats from the previous course, and 
develop a project to carry out in the second course. One of the goals of 
the course is to develop teamwork and organizational skills so we do a lot 
of group work. In the past, individuals have passed the course even though 
they have done poorly on the exams because they have had partners carry 
them through the stats and difficult concepts.Then they had a terrible time 
in the following course. This year I was determined to be sure that each 
individual had the necessary skills before they go on, so we have lots of 
tutoring, hands-on labs and homework to go over the critical concepts and 
stats. I've slowed down and dropped whole chapters to spend more time on 
key concepts. For the second exam, I told the students that they would have 
a portion of the exam (I'm thinking 20%) in which they would demonstrate 
their understanding of design and statistics in the lab in very small 
groups. The idea was to split my 2 hour lab class into 4 --30 minute 
periods and have 5-6 students in at a time. Then I would ask them to upload 
a data set to spss, run the appropriate analyses (2-way anova) , print it 
and interpret the print out (what effects were significant) what followup 
tests to do.

So here is the question: On the one hand, I've never seen the students work 
so hard in preparation for this, on the other I fear that about 1/3 of them 
will fail this section, due in part to lack of understanding and in part to 
anxiety over the exam format. I hate to destroy the class moral which is 
already fragile, as they struggle with the complexities of factorial 
designs. Have any of you done this sort of individual testing? if so, what 
have you found to work?
Thanks for your help-Dawn


Dawn G. Blasko Ph.D.
Associate Professor of Experimental Psychology
Penn State Erie, The Behrend College
Station Road
Erie, PA 16563-1501
Office phone: 814-898-6081
http://www.pserie.psu.edu/hss/psych/blasko.htm



Night vision (Student question)

2000-11-06 Thread Drnanjo
Folks,

Are there any explanations for variations in the acuity of night vision from person to person (other than owning night vision goggles)?  

A student  asked what the explanation would be, according to her, her brother and husband see better in the dark than she does . I also wonder since this is a subjective and ancedotal account, if night vision has been studied with this in mind (finding out who might have better than average night vision and what neuroanatomical or neurochemical conditions would make this so.)

Thanks for any help you can give me.


Nancy Melucci
Los Angeles Harbor College



Re: The madness continues: the guess mess

2000-11-06 Thread Drnanjo
You can appeal to authority if you wish but this is not relevant to the mathematical probabilities involved. ETS has its own agendas. I would need to see loads of data  to be convinced that it wouldn't hurt a number of students on an individual level to guess on items where they can't eliminated at least two items.

You may think me stupid or dense, and perhaps I am, but I would STILL advise high school students taking the SAT to skip on items where they can't eliminate any items, or do something to narrow the range of possible answers.

Nancy M.