i see that you have groups of weak and strong ... though, cutting at the
mean really means readers with less than the mean and and those with scores
more than the mean ... whether this means WEAK/STRONG depends on the actual
scores ... but, i digress
what are the TWO treatments?
if what i see here is right ...
1. you have pre and post
2. weak and strong
3. treatment 1 and 2??????
if you have randomly assigned Ss to the 2 levels of #3 ... and then sorted
the Ss into weak/strong for purposes of analysis ...
you would have a blocking variable for level of ability ... low/high
this would call for (if i am reading it correctly) a 2 by 2 by 2 anova ...
that's one way to do it with #1 being a within Ss factor ... and #2 and #3
being between Ss factors ....
the interactions might be of most difference ... asking if the weak or
strong change the most ... while perhaps ALL change ... it a positive
direction
At 06:54 PM 6/19/00 +0100, Donal wrote:
>Greetings All,
>
>I'm currently analysing data resulting from a study of children's reading
>ability. The study involves two treatments and each child's reading ability
>was measured before and after the application of one of the treatments.
>Thus, each child received one or the other (but not both) of two possible
>treatments. The children are divided into two groups:
>
>Weak readers: those whose pre-treatment reading score was less than the mean
>pre-treatment reading score
>Strong readers: those whose pre-treatment reading score was greater than the
>mean pre-treatment reading score
>
>Anyhow, I would like to test (for each treatment) whether or not the change
>in the reading score (Post-treatment score - Pre-treatment score) is the
>same for weak readers and strong readers. I have atempted to test this by:
>
>1. Creating a new variable, "Change"
> Change = Post-treatment score - Pre-treatment score
>
>2. Using a two-sample t-test to determine whether or not the mean value of
>"Change" measured over the weak readers is significantly different from the
>mean value of "Change" measured over the strong readers
>
>However, I am not certain that this is the best way to test my hypothesis,
>if anyone can suggest a better way, I'd be very grateful for their
>assistance.
>
>Similarly, I'd like to test whether or not the change in the reading score
>is the same for each treatment. I have attempted to test this by:
>
>1. Creating a new variable, "Change"
> Change = Post-treatment score - Pre-treatment score
>
>2. Using a two-sample t-test to determine whether or not the mean value of
>"Change" measured over treatment A is significantly different from the mean
>value of "Change" measured over treatment B
>
>Again, if anyone knows of a better way of performing this test, I'd be very
>appreciative if they would let me know about it.
>
>Thanks in advance,
>D�nal.
>
>
>
>
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==============================================================
dennis roberts, penn state university
educational psychology, 8148632401
http://roberts.ed.psu.edu/users/droberts/droberts.htm
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This list is open to everyone. Occasionally, less thoughtful
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