@LisaDeBruine You can even make it much 'more' bimodal and still satisfy the normality assumption. "DV ~ normal" probably is the most common mistake w.r.t. statistical assumptions.
https://t.co/dZimZjX0DZ https://t.co/OW7xqehpQP
@KMKing_Psych Yes! I assign this review of common misconceptions to my grad quant students in clinical psychology research. I think Figure 1 is a nice simple example of non-normally distributed outcome that could have normal residuals following analysis. https://t.co/p1ERbTMwGt via @thePeerJ
@Research_Tim Simulate some data; show them a scatterplot of with a two-level x variable with a large slope, then show them the (obviously bimodal) y variable, then show the (Gaussian) residuals. (Fig 1 from @CaAl's https://t.co/nbE9d7JQtB) https://t.co/vdu49ukTDN
@Research_Tim Thinking that X or Y themselves have to be normally distributed rather than the residuals, is a common misconception https://t.co/dZimZjX0DZ
Here: Depending on the values of the covariate, the distribution of the residuals can take almost any form
@MaartenvSmeden @DanielOberski @statsepi @robertstats Indeed, it's common. What's even more common, is that people said "We checked for normality" without explicitly stating *what* they checked and *how* they checked it.
See this meta-analysis by @anja_franziska and me: https://t.co/dZimZjX0DZ
Eek! More than 90% of pubs in clinical psyc journals using regression don't report tests of regression assumptions...those that do report them, often report incorrect assumptions (normality of variable instead of residual). https://t.co/p1ERbTuVhT via @thePeerJ
@seriousstats @deevybee To biased esitmators, just sub-optimal ones (cf https://t.co/dZimZjX0DZ ) 3/2 (apologies for my inability to count tweets properly)