Why ANCOVA?

Hi Group,

I need to repeat an analysis that was conducted on a smaller dataset,
but after looking at the previous statistician's methods, I'm a little
confused at why she chose to use ANCOVA. Any insight would be
appreciated!

Response Variable: Scores on 36 different Tests
Main Predictor of Interest is Treatment Type (1 or 2)
Data was collected from different individuals in each treatment group.

What she did:
1. Chi-square tests between Treatment Type and Clinical/Demographic
Factors (i.e. Race, Sex, Age) and identified 3 significant variables.

2. ANCOVA analyses for each continuous test score (36 separate
ANCOVAs) to identify significant differences between patients in
Treatment 1 vs. Treatment 2, while controlling for 3 categorical
demographic variables.

I don't have that much experience in ANCOVA, but I thought this is
used to control for continuous "covariates", or does it apply to
categorical ones too? Would a multiple linear regression in this case
be enough to control for the significant categorical variables
identified by the chi-square analyses?

Thanks very much,
Jean

.

Relevant Pages

  • Re: Why ANCOVA?
    ... Data was collected from different individuals in each treatment group. ... ANCOVA analyses for each continuous test score (36 separate ... Would a multiple linear regression in this case ... ANOVA "factors" with more than two levels ...
    (sci.stat.edu)
  • What research design do I use?
    ... (correlational design, no treatment provided, just measures to assess ... attitudes) and am interested in doing analyses on these groups. ... am measuring the same person on 13 measures so ANOVAs/MANOVAs may be ...
    (sci.psychology.research)
  • Re: Analysing baseline and follow-up measurements
    ... January 2005) have shown that in randomised trials where for ... example two treatment outcomes are compared, the ANCOVA aproach using ... the baseline score of the outcome as covariate is superior to analysing ... thes changes vary across treatments, ...
    (sci.stat.consult)
  • Re: Reporting effect sizes for McNemars test
    ... appropriate effect size index to report with my analyses. ... be the difference in pairs favored by one treatment. ... That is reference to a t-statistic. ...
    (sci.stat.math)
Quantcast