1. M

    Control variables in mediation analysis?

    Hi, I want to conduct a mediation analysis, which will investigate whether the change in depressive symptoms during treatment (time) is mediated by the change in OCD symptoms. Currently, I have time as my predictor, OCD symptoms as my mediator and depressive symptoms (at time t+1) as my...
  2. A

    Reporting Dummy Variables and Determining Significance

    Hi all, I was just wondering, how does a person determine the significance of a categorical variable in a hierarchical regression model if one dummy variable is significant and the other is non-significant? So basically, the categorical variable (X) I am examining has three levels, so...
  3. C

    Propensity score matching - pre-treatment outcome variable

    Hi all, maybe this rather a silly question but I have not found anything helpful. I have two groups of samples which are basically a treatment and control group. My task at hand is to compare a certain variable between those two groups, which however is not appearing after the treatment...
  4. X

    Determining minimum control group size for purposes of verifying lift

    I have the following scenario: - We want to send out an email blast to existing members to promote an upsell. - We are quite positive the email blast will increase the number of upsells, but we are interested in determining by how much. - So we want to keep a control group for...
  5. L

    Evaluating data via a three-way (2 x 3 x 4) ANCOVA

    Biomedical researcher here, trying to figure out how to analyze the results of a study on cell culture conditions. Three IVs were chosen: compound A (2 levels), compound B (3 levels), and compound C (4 levels). Cells were grown in microplate wells, 4 wells for each of the 24 permutations of the...
  6. A

    test of significance for comparing change between two groups

    What test for significance is best to use to test the difference between the change of a categorical variable in a control group and the change in a pilot group? I do not think I can simply compare the 'after' for each because the 'before' for the two groups was statistically different - they...
  7. P

    sample size for control and treatment groups

    hello everyone, I am in the process of designing an agricultural experiment in which I want to compare a series of variables between a group of manufacturers who use a mobile telephone app (n=15,000) is my treatment group and another group that does not (n=100,000) which is my control group...
  8. F

    Control for yearly effects

    Hi everybody, of course, I tried to find a thread with an answer about my topic. Unfortunately without success. I ran a multi regression analysis with 8 control variables and one explanatory variables to explain my dependent variable. The date is compiled between the years 1990 and 2000...
  9. A

    Shewhart Control Chart Calculate Alpha Errors Under Rules

    Two decision rules are given here. Assume they apply to a normally distributed quality characteristic and the sample size is n=5. Rule 1: The control chart uses the three-sigma control limits. If one or more of the next seven samples yield values of the sample average that fall outside the...
  10. A

    Pre-Test/Post-Test With Multiple Tests Running

    Very new to this statistics thing and could use some help deciding how to run the data for this. 60 participants (30 control/30 intervention). Each person is being given 5 different likert-scale assessments, oral cortisol swabs, blood pressure pre-test and post-test. I'm studying the effects of...
  11. G

    [JMP 9] Manova with controlling variables

    Hi there, Where (in which box) do I add control variables running a Manova (fit model) in JMP 9? Thank you gav
  12. R

    Which sig test to use?

    I want to compare a change in 2 experimental groups to the change in 2 control groups. So I have results for one sample, then retested among another indepedent sample, and was tested among a control group, then retested among a different control. For example, the 1st experimental group had a...