When scores change over time but the extent of

In this BGB-324 situation, using RA as an index of R 'BGB-324' is invalid because the key assumption of equal residual variance across individuals is violated: individuals whose behaviour changes markedly over time (a substantial time trend) have higher residual variance than individuals who maintain the same expected values over time (no time trend). Similarly, RC cannot provide a valid index of R because atomic number assumes that individuals all have the same time trends.