Persistent individual differences despite standardisation. 40 female mice of the inbred strain C57BL/6 were kept in strictly standardised conditions and tested at PND 85 and PND 120 in an open field (OF) test for locomotor behaviour. Despite genetic and environmental standardisation considerable individual differences emerged in both tests. Pearson's product-moment correlation analysis revealed a significant correlation between the different tests explaining 13% of the variance. Additionally to the regression line (black) the 95% confidence band (inner red lines) and the 95% prediction band (outer blue lines) are drawn.