A Comparison of the Validity of High School Grade Point Averages in Relation to ACT Scores of Public and Private School Students in Mississippi

The purpose of this correlational research study was to investigate the validity of cumulative HSGPAs in relation to ACT scores and to compare the findings from public and private schools. A total of 550 students from a public school district in a suburb in Mississippi were included in the sample along with 111 private school students located within the same area. A regression model was used to determine first if there were correlations among HSGPA and ACT at each school respectively. Results indicated that a moderately strong positive correlation exists between HSGPAs and ACT scores at both private and public schools included in the sample. In addition, a test of parallelism was used to determine if there was a difference in correlations between HSGPA and ACT scores when the type of school was used as an indicator variable. Significant differences in correlations were found when type of school was used as an indicator variable. The findings of the study suggest there are differences in correlations among HSGPA and ACT scores for students at private and public schools which lead to implications regarding a difference in validity of HSGPA in relation to ACT scores for students at different schools included in the sample.