+ Reply to Thread
Results 1 to 6 of 6

Thread: ANOCOVA or Gain score?

  1. #1
    Points: 25, Level: 1
    Level completed: 49%, Points required for next Level: 25

    Posts
    3
    Thanks
    3
    Thanked 0 Times in 0 Posts

    Post ANOCOVA or Gain score?




    Hi everyone,

    I'm a newbie Ph.D. student and encountering an issue regarding which analysis to use for my study. Please help me out if you have some time.

    My study design is basically two treatment groups and one control group with pre and posttest. However, the pretest scores for one of the variables have significant differences across the three conditions which I need to control for that. I tried ANCOVA and the homogeneity of variance was violated. Unfortunately, the group sizes were different (N=56/35/21). I know there has being controversies about using gain score analysis. I wonder what other analysis I can use. Thank you for your time.

  2. #2
    TS Contributor
    Points: 17,749, Level: 84
    Level completed: 80%, Points required for next Level: 101
    Karabiner's Avatar
    Location
    FC Schalke 04, Germany
    Posts
    2,540
    Thanks
    56
    Thanked 640 Times in 602 Posts

    Re: ANOCOVA or Gain score?

    The third (and straightfoward, IMHO) option would be repeated-measures ANOVA with an
    additional grouping factor.

    With kind regards

    K.

  3. The Following User Says Thank You to Karabiner For This Useful Post:

    mrsi (05-27-2016)

  4. #3
    Points: 25, Level: 1
    Level completed: 49%, Points required for next Level: 25

    Posts
    3
    Thanks
    3
    Thanked 0 Times in 0 Posts

    Re: ANOCOVA or Gain score?

    Thank you, sir, for the reply. Would you please explain more? What would be the additional grouping factor? Thank you so much for your time.

  5. #4
    TS Contributor
    Points: 17,749, Level: 84
    Level completed: 80%, Points required for next Level: 101
    Karabiner's Avatar
    Location
    FC Schalke 04, Germany
    Posts
    2,540
    Thanks
    56
    Thanked 640 Times in 602 Posts

    Re: ANOCOVA or Gain score?

    You wrote that you have pre-post-data and a group factor with 3 categories.

    With kind regards

    K.

  6. The Following User Says Thank You to Karabiner For This Useful Post:

    mrsi (05-28-2016)

  7. #5
    Points: 25, Level: 1
    Level completed: 49%, Points required for next Level: 25

    Posts
    3
    Thanks
    3
    Thanked 0 Times in 0 Posts

    Re: ANOCOVA or Gain score?

    Thank you again for your kind reply. I apologize for my confusion. One more questions. I used a 2 x 3 mixed ANOVA in my original manuscript. But the reviewer commented that I should control for the differences in pretest by using other analysis. Is there any way I can address this issue?

  8. #6
    TS Contributor
    Points: 17,749, Level: 84
    Level completed: 80%, Points required for next Level: 101
    Karabiner's Avatar
    Location
    FC Schalke 04, Germany
    Posts
    2,540
    Thanks
    56
    Thanked 640 Times in 602 Posts

    Re: ANOCOVA or Gain score?


    So you already had used the mixed ANOVA approach which I later recommended?

    Unfortunately, I do not know an analysis which can really control for differences in baseline values.
    Maybe your reviewer has the idea that using baseline as covariate can eliminate baseline differences.

    Some discussion about ANCOVA versus gain scores (the latter produce results equivalent to
    mixed ANOVA in case of 2 time points) can be found here http://wiki.math.yorku.ca/index.php/...ed_gain_scores

    With kind regards

    K.

  9. The Following User Says Thank You to Karabiner For This Useful Post:

    mrsi (05-30-2016)

+ Reply to Thread

           




Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts






Advertise on Talk Stats