Since educational research is commonly concerned with learning, change scores or growth scores or difference scores as they are frequently called measure differences in performance between two occasions. Problems arise in the examination of change scores and measurement on more than two occasions is now commonly employed in studies of change or growth.
Ceteris paribus is a Latin phrase with the meaning of "all other things being equal".
The central limit theorem is a statistical proposition that establishes that the larger the sample size, the more closely the distribution of values recorded for the sample will approach a normal distribution. This is true even if the values are not normally distributed in the population from which the sample was drawn.
In a census, data are collected from an entire population rather than from a sample drawn from that population.