A cross-sectional study compares different individuals to each other at the same time—it looks at a cross-section of a population. The differences between those individuals can confound with the effect being explored. For example, in trying to determine the effect of age on sexual promiscuity, a cross-sectional study would be likely to confound the effect of age with the effect of the mores the subjects were taught as children: the older individuals were probably raised with a very different attitude towards promiscuity than the younger subjects. Thus it would be imprudent to attribute differences in promiscuity to the aging process. See longitudinal study.