ADDING A DIMENSION - TIME AS A FACTOR IN THE GENERALIZABILITY OF PREDICTIVE RELATIONSHIPS

Trends in predictive validity coefficients across time or repeated performance assessments show significant trends. Commonly used predictors show decreasing validities for the prediction of temporally more remote performance assessments. Within-study corrections for statistical artifacts across performance assessments increased the negative slopes of the regressions of predictive validities on ordinal position of performance assessment. The average corrected validity decrement from initial to final performance assessment was -.60; the trimmed average decrement was -.45; the median decrement was -.29. The average within-study correlation between predictive validity and time of performance assessment was -.80. An analysis of stability coefficients of Time Period × Time Period performance assessments revealed similar findings. Several theoretical explanations are discussed as reasons for predictive validity decrements.