title: Statistic model beyond ANOVA using SPSS
body: <p>I have two groups in which I compare two times (before and after treatment). </p>
  
  <p>At first, I tried an repeated measures ANOVA and observed significant difference between groups. However, I have the following question: baseline means (time 1) are very different between groups and we fear that the significant result of ANOVA is due to this difference between baselines. </p>
  
  <p>Therefore, we consider using another statistical model, specifically mixed models. However, the SPSS does not run telling me that "no valid case was found". </p>
  
  <p>I talked to a statistician who said the problem is that the number of observations (rows) is less than the number of columns (dependent variables). </p>
  
  <p>Would anyone know if this information makes sense? And does anyone know of any statistical model that would help us control this difference between baselines using SPSS?</p>