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How are two variables measured before and after an intervention?
I have two variables that I am measuring before and after an intervention. Ideally, if one variable increases after the intervention, the other should too. Both variables measure different things and both are relative or in other words percentages. So I have variable a (before and after) and variable b (before an after) for 20 subjects.
When to attribute success to intervention or posttest?
When you see a large enough difference between the pretest and posttest, you are tempted to attribute it to the intervention and claim success of the experiment. However, the half-a-dozen single-group threats challenge this interpretation. Read up on single-group Threats on WWW. Good luck.
How to measure the intervention process, an assessment of?
The use of process evaluation, defined as the evaluation of “individual, collective or management perceptions and actions in implementing any intervention and their influence on the overall result of the intervention.” Nytrø et al.
Which is test is appropriate for comparing pre and post?
Even the fact that your subjects are hungrier, happier, or more tired during one evaluation than the other could have more effect than the actual treatment. There is no statistical test that can over come these limitations (there are some alternate study designs that may help some).
Is the pre test measure a covariate or outcome?
The pre-test measure is not an outcome, but a covariate. This model assesses the differences in the post-test means after accounting for pre-test values. The advisor said repeated measures ANOVA is only appropriate if the outcome is measured multiple times after the intervention.
When does repeated measures ANOVA need to be used?
The advisor said repeated measures ANOVA is only appropriate if the outcome is measured multiple times after the intervention. The more she insisted repeated measures didn’t work in Nancy’s design, the more confused Nancy got.
What was the response variable in Nancy’s study?
Nancy had measured a response variable at two time points for two groups: an intervention group, who received a treatment, and a control group, who did not. Both groups were measured before and after the intervention.