Sample size

To some extent, the small sample sizes for the evaluation of the three YouthARTS programs were due to program design and were thus unavoidable. An important feature of many arts programs, like Art-at-Work in Atlanta and Youth Arts Public Art in Portland, is the small youth-to-artist ratio. Although this allows for quality one-on-one instruction of the participants, it creates a challenge for the evaluator. Small sample sizes preclude testing for statistical significance (determining whether observed changes occur by chance or because of the intervention). Additionally, small sample sizes make it difficult to generalize the findings to the broader population of at-risk youth. Although an evaluator cannot control the size of a program, steps can be taken to avoid small sample sizes resulting from missing data. Because data were not uniformly collected for all youth at all data collection points, many youth had to be excluded from the analyses. Every effort must be made to obtain complete data for all youth involved in the program and comparison groups.