This study demonstrates that the researcher can obtain markedly different results depending on how the missing data are handled. Missing data theory suggests that listwise deletion and single imputation procedures should not be used to account for missing information, and that MI has advantages with respect to internal and external validity when the assumption of missing at random can be reasonably supported. (PsycINFO Database Record (c) 2012 APA, all rights reserved) (Source: Experimental and Clinical Psychopharmacology)