Avoiding Linear Dependencies in Artificial Data Sets

2001-03-12 Thread jim clark
Hi I like to use small, artificially generated data sets with integer parameters to introduce analyses. Often, however, I find it difficult to avoid undesirable contingencies among the scores (e.g., linear dependencies in within-subject designs). Is there an algorithmic way to generate such

IRT/Rasch Modeling with SAS?

2001-03-12 Thread Lee Creighton
Hi all, I am working on a dissertation that analyzes some international tests of mathematics achievement. I need to use the responses (which can be considered "correct"/"incorrect") and estimate an IRT (Item Response Theory) model to describe the test. In a nutshell, assume the test measures a

Re: On inappropriate hypothesis testing. Was: MIT Sexism statistical

2001-03-12 Thread jim clark
Hi On 12 Mar 2001, Radford Neal wrote: Yes indeed. And the context in this case is the question of whether or not the difference in performance provides an alternative explanation for why the men were paid more (one supposes, no actual salary data has been released). In this context, all

Re: On inappropriate hypothesis testing. Was: MIT Sexism statistical bunk

2001-03-12 Thread dennis roberts
At 02:25 PM 3/12/01 +, Radford Neal wrote: In this context, all that matters is that there is a difference. As explained in many previous posts by myself and others, it is NOT appropriate in this context to do a significance test, and ignore the difference if you can't reject the null

One tailed vs. Two tailed test

2001-03-12 Thread auda
Hi, all, We are testing a group of subjects on their performance in two different conditions (say, A and B), and we are testing them individually. We have an alternative hypothesis that reaction time in condition A should be longer than in condition B, so we perform a one-tailed t test. However,

Re: Avoiding Linear Dependencies in Artificial Data Sets

2001-03-12 Thread Bob Wheeler
It isn't actually that easy, in the sense that most data humans make up has a low efficiency with respect to design criteria -- the determinant of the cross-product matrix tends to be small. The simplest way is to use a computer program that calculates algorithmic designs. jim clark wrote:

Re: One tailed vs. Two tailed test

2001-03-12 Thread Thom Baguley
auda wrote: Hi, all, We are testing a group of subjects on their performance in two different conditions (say, A and B), and we are testing them individually. We have an alternative hypothesis that reaction time in condition A should be longer than in condition B, so we perform a

Re: On inappropriate hypothesis testing. Was: MIT Sexism statistical bunk

2001-03-12 Thread Irving Scheffe
Jim: I agree with Radford Neal's comments, and urge careful reconsideration of the foundation behind some of the comments made. For example, suppose you had a department in which the citation data were Males Females 12220 1298 2297 1102 The male with 12220 is, let's

Re: On inappropriate hypothesis testing. Was: MIT Sexism statistical

2001-03-12 Thread jim clark
Hi On Mon, 12 Mar 2001, Irving Scheffe wrote: Jim: For example, suppose you had a department in which the citation data were Males Females 12220 1298 2297 1102 When I said outlier, I had in mind hypothetical data of the following sort (it doesn't matter to me whether

Re: One tailed vs. Two tailed test

2001-03-12 Thread Jerry Dallal
auda wrote: Hi, all, We are testing a group of subjects on their performance in two different conditions (say, A and B), and we are testing them individually. We have an alternative hypothesis that reaction time in condition A should be longer than in condition B, so we perform a

Re: Avoiding Linear Dependencies in Artificial Data Sets

2001-03-12 Thread Elliot Cramer
I'm not clear on what your design is but it seems that the problem is in the between S effect not within. Note that you only have 4 df within and 4 dependent variables = Instructions for joining and leaving this list and

Speaking of ANOVA in SPSS...

2001-03-12 Thread Will Hopkins
I'm trying to reduce all stats to a few simple procedures that students can do EASILY with available stats packages. A two-way ANOVA or an ANCOVA is as complex as I want to go. I thought SPSS would do the trick, but I was amazed to discover that it can't. Here's the example. I want students

Re: One tailed vs. Two tailed test

2001-03-12 Thread Will Hopkins
At 7:34 PM + 12/3/01, Jerry Dallal wrote: Don't do one-tailed tests. If you are going to do any tests, it makes more sense to one-tailed tests. The resulting p value actually means something that folks can understand: it's the probability the true value of the effect is opposite to what

Re: One tailed vs. Two tailed test

2001-03-12 Thread Donald Burrill
On Tue, 13 Mar 2001, Will Hopkins wrote in part: Example: you observe an effect of +5.3 units, one-tailed p = 0.04. Therefore there is a probability of 0.04 that the true value is less than zero. Sorry, that's incorrect. The probability is 0.04 that you would find an effect as large as