I would run a repeated measures ANOVA. You have 2 Between subjects factors (A & B) and 1 Within subjets factor (Time (pre vs post). This gives one 3-way interaction and three 2-way interactions. These could give you info about a possible moderation effect.

Here you have our pre-post paper and then our paper with more advanced statistics:

Jos Feys, I think Maddie meant that she has the model you describe plus one continuous "moderator" variable. The usual way of doing classical mixed design ANOVA in SPSS is via the GLM command (Analyze > GLM > Repeated measures in the GUI). It does allow inclusion of continuous covariates in the model. But there are drawbacks to using GLM, which makes the MIXED command (i.e., a multilevel model approach) more appealing. See the following UCLA websites for examples of how to use MIXED for repeated measures designs.

• https://stats.idre.ucla.edu/spss/seminars/repeated-measures/
• https://stats.idre.ucla.edu/spss/seminars/spss-mixed-command/

If you do want to try the classical GLM > Repeated Measures approach, see this letter to the editor for some tips.

• https://pdfs.semanticscholar.org/7df3/70e0a23ece5f2a99653e061a9bf0df45241e.pdf?_ga=2.3473715.2048716209.1556806946-1431401893.1539959493

HTH.

I will take a middle ground. You should add interaction (moderation) variables to your model. These are of the form b*x1*x2. You should then build your model according to the attached notes. N.B. Prof Davidian is an expert in this subject. The link is:

https://www4.stat.ncsu.edu/~davidian/st732/notes.html

for a general overview see:

https://www.bing.com/search?q=moderation+and+interaction&qs=n&form=QBRE&sp=-1&pq=moderation+and+interaction&sc=2-26&sk=&cvid=C928740A37C54C7AAA48238E3AF34DFC

Best, David Booth