=+2. Figure 13 shows a model to test the effects of participation in Head Start on children’s cognitive ability. This example is a classic reanalysis of a controversial quasi-experiment; I have seen variations of it presented in Kenny (1979) and Bentler and Woodward (1978), among others. The measured background variables in the model include measures of mother’s and father’s educational attainment, father’s occupational status, and family income. Head Start was hoped to improve participants’cognitive skills, and the latent Cognitive Ability outcome was indexed by scores on two tests: the Illinois Test of Psycholinguistic Abilities (ITPA) and the Metropolitan Readiness Test (MRT). The Head Start variable is a dummy variable coded