Some non-randomized constructed comparison groups for evaluating age-related outcomes of intervention programs

Author(s): Ryan, C. S., Green, B. L.

Journal/Book: Am J Eval. 1999; 20: 100 Prospect St, PO Box 811, Stamford, CT 06901, USA. Jai Press Inc. 213-226.

Abstract: The evaluations of many intervention programs for young children are hampered by the lack of untreated comparison groups. Simple pre-post comparisons or more elaborate growth profile analyses within a single treatment group cannot separate changes associated with the treatment from normal developmental changes typical of the participant population. To address this issue, some non-randomized constructed comparison strategies that can be used to evaluate interventions are outlined and illustrated for outcome variables that would be expected to change over age if no treatment were given. Such a dependent variable might include general indices of developmental progress in young children, which may decline over the first few years of life in low-income, high-risk samples or may increase over age in middle-class groups suffering adverse perinatal circumstances and disorders even without special interventions. The proposed strategy consists of determining an expected age function for the dependent variable using pretest scores (if participants enter the treatment program at different ages) or using pretest scores of older siblings who vary in age at the start of the program, and then calculating an age-adjusted expected posttest score against which actual posttest performance may be evaluated. This approach also permits analysis of participants enrolled in the treatment for varying lengths of time and over somewhat different age spans.

Note: Article McCall RB, Univ Pittsburgh, Off Child Dev, Policy & Evaluat Project, 121 Univ Pl, Pittsburgh,PA 15260 USA

Keyword(s): CHILDREN; INDEX

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