Criteria for suitable research designs for use with large databases are suggested and analyzed. The advantages and disadvantages of several types of quasi-experimental designs are compared. Examples are taken from the authors' research with data from the Manitoba Health Services Commission. (Author/AL)

The relationships among grade, substance assessed, and type of measurement and statistical analysis used in the detection of external validity threats resulting from subject attrition in a modal follow-up study were examined in 6 successive 2-year panels of adolescents, including 4,819 overall stayers and 1,897 dropouts. (SLD)

The problem of the appropriate comparison group for bereavement studies is discussed. The use of the retrospective pretest design is illustrated through a longitudinal study of bereavement outcome following pregnancy loss, involving 138 bereaved women and a comparison group of 215 currently pregnant women. (SLD)

Evidence is presented that strengthens the argument against comparison group research strategies. Results from a study of youth attitudes related to the California Conservation Corps involving 528 participants and 668 comparisons indicate that the comparison group may not adequately represent the nontreatment state. (SLD)