1. Catalog of Bias: Chronological Bias
Definition: earlier recruited study participants allocated into one intervention group, and later participants ending up in another group.
It can take time to recruit participants into a study, whether observational or interventional, and sometimes differences occur between those recruited earlier in the process and than those recruited later.
In randomized trials, using small block sizes for randomization can reduce chronological bias, but must be balanced with the resulting risk of selection bias
Chronological bias in randomized clinical trials arising from different types of unobserved time trends.
Tamm M, Hilgers RD.Methods Inf Med ;53(6): doi: /ME
Catolog of bias: Spencer E, Heneghan C .CEBM