Timeline for Should I use ANCOVA or multiple regression with dummy variables?
Current License: CC BY-SA 3.0
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| Dec 11, 2012 at 10:51 | comment | added | Camille | @PeterEllis. Thanks. You are absolutely right that my colleague is suggesting a type of stepwise regression which is probably not appropriate here. As ANCOVA and Regression are mathematically the same, and all relationships are founded on a conceptual model, I think my issue really comes down to the way the results are presented to a potential reviewer who may be more used to seeing ANCOVAs. As I need the interactions to test the hypotheses, I am leaning towards stage 1: all single variables, stage 2: all interactions. Does anyone have a view on that? | |
| Dec 11, 2012 at 0:14 | comment | added | Peter Ellis | +1. The issue is not ANCOVA v regression (they are the same) but how you build a model. The colleague's proposed approach sounds like a variant on stepwise regression, and will have all the associated problems as Peter Flom points out. See stats.stackexchange.com/questions/13686/… . | |
| Dec 10, 2012 at 13:06 | comment | added | Peter Flom | As I said, ANCOVA and regression are mathematically equivalent. Interactions may be easier to add in the regression model, but that would be because of notation and software implementation. | |
| Dec 10, 2012 at 12:10 | comment | added | Camille | Clearly this is not ground-breaking stuff so small effect sizes are indicative that context doesn't mean much here. However I still have the question of how to test the interactions and whether the regressions are a better technique. | |
| Dec 10, 2012 at 11:34 | comment | added | Peter Flom | Oh, I know about psychology! I make my own small efforts to change things, but .... yes, p value is still (all too often) viewed as the most important (or even only important) thing. | |
| Dec 10, 2012 at 11:28 | comment | added | Camille | I have the same concern regarding my colleagues approach. I agree about statistical significance but unfortunately psychology is a field where the p value rules!! I should also say that I have no problem with reporting a lack of significant findings or with very small effect sizes as negligible results are informative in themselves regarding the lack of importance in the real world. | |
| Dec 10, 2012 at 11:08 | history | answered | Peter Flom | CC BY-SA 3.0 |