In article <8umakk$o26$[EMAIL PROTECTED]>,
Dennis <[EMAIL PROTECTED]> wrote:
>Hello Newsgroup,
>I'm searching for real good books on stats. I'm a student of psychology and
>we've been taught very much stats. But I read all the time your postings and
>wonder why I've never heard about that what I read. So what I'm searching
>for is e.g. a profound heuristic, which model or technique is to be used on
>a specific question of a research or evaluation problem. How important are
>the assumptions of those techniques. Every time I read articles, there are
>used techniques like multiple regression without any hint of data
>examination, prove of assumptions etc. Often there are used equation models
>with only N=20, factor analysis with only a two-to-one ratio of observations
>and variables or with dichotomous variables factor analyzed etc. Or there
>are used techniques which I don't even know. I don't know much about time
>series, biostatistics, neural networks or mathematical system theory. After
>three and a half years of stats lessons I'm more and more confused and
>insecure. Esp. when I'm thinking about my diploma thesis or thinking of
>working as a "scientist practitioner" psychologist I don't know how to use
>my knowledge or build up an applied oriented knowledge base. Maybe some of
>you can help me with this?
>Hopefully and with much regards
>yours Dennis
You seem to have had courses in statistical techniques,
but nothing which I would call a course in statistics.
You have been taught the rituals of the statistical
religion, evolved like alchemy before anyone understood
the principles of chemistry.
You need to learn probability (not how to compute answers,
but what it means, and that nothing in reality is normal)
and decision theory.
I have some commandments for clients and consultants
which you might find enlightening.
I am often requested to repost my five commandments. These are
posted here without exegesis.
For the client:
1. Thou shalt know that thou must make assumptions.
2. Thou shalt not believe thy assumptions.
For the consultant:
3. Thou shalt not make thy client's assumptions for him.
4. Thou shalt inform thy client of the consequences
of his assumptions.
For the person who is both (e. g., a biostatistician or psychometrician):
5. Thou shalt keep thy roles distinct, lest thou violate
some of the other commandments.
The consultant is obligated to point out how their assumptions affect
their views of their domain; this is in the 4-th commandment. But the
consultant should be very careful in the assumption-making process not
to intrude beyond possibly pointing out that certain assumptions make
large differences, while others do not. A good example here is regression
analysis, where often normality has little effect, but the linearity of
the model is of great importance. Thus, it is very important for the
client to have to justify transformations.
There are, unfortunately, many fields in which much of the activity
consists of using statistical procedures without regard for any assumptions.
--
This address is for information only. I do not claim that these views
are those of the Statistics Department or of Purdue University.
Herman Rubin, Dept. of Statistics, Purdue Univ., West Lafayette IN47907-1399
[EMAIL PROTECTED] Phone: (765)494-6054 FAX: (765)494-0558
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