"Attrition bias" refers to a situation where the people who drop out or leave a study or research are different from those who stay, leading to biased or unreliable results. Full definition
Limitations include attrition bias due to the high dropout rate and bias due to the fact that the assessors who administered the measures were not blinded to treatment conditions. (cebc4cw.org)
To test the effect of attrition bias in all four possible groups, we conducted a one - way ANOVA. (journals.plos.org)
We were worried about attrition bias in a few studies because they never told us the number of women who started the study, so there was no way for us to determine if unequal attrition occurred. (birthingnaturally.net)