What Is Selective Attrition?
This tendency can threaten thevalidityof a psychological experiment.
Imagine that researchers are doing a longitudinal study on how cardio exercise impacts cognitive functioning as people age.
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Selective attrition will happen naturally with a study that occurs over such a long period of time.
But what if certain groups of individuals become more prone to selective attrition?
Suppose that widowers tend to drop out of the study more frequently than those who have a surviving spouse.
Internal validitycan also be a problem with there are different attrition rates between thecontrol groupsand theexperimental groups.
A Word From Verywell
Some attrition is only natural in psychology studies.
Very high levels of attrition, however, can hurt the validity of the results.
Research has also shown that selective attrition can also impact research results.
In one study, for example, researchers found that attrition led to overestimates of the effects of treatment.
Salthouse TA.Selectivity of Attrition in Longitudinal Studies of Cognitive Functioning.J Gerontol B Psychol Sci Soc Sci.
1987;12(3):297-302. doi:10.1016/0306-4603(87)90044-x
