Microsoft Word Heckman final 2007-03-22c jsb doc
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- Evidence from Enriched Preschool Programs
25 the young, especially in disadvantaged populations. 46
Two matters of concern arise in using this evidence to guide policy. First, it is associational or correlational. It establishes empirical relationships that may or may not be causal. Second, while family factors matter, it is far from obvious how to improve families. We cannot easily raise the education of parents, nor can we improve their IQs. The evidence presented in Armor, in figures 10-11, and in the other studies reviewed here suggests that early investment is productive. But traditionally, the early years of a child’s life are the exclusive province of the family. The tough question is how to enrich the family and at the same time preserve the benefits of parents? An accumulating body of evidence on voluntary interventions points the way. We now turn to a review of the evidence on the benefits of these voluntary interventions. In the past 40 years, many voluntary interventions have been devised to improve the early years of children by supplementing the resources of disadvantaged families. These family supplements do not actively intrude on family life, yet they enrich the early years of the child. Some of these interventions have been implemented using random assignment. Packages of enriched environments are randomly assigned to children in disadvantaged environments, while children in comparable families are randomly denied access to the enriched treatment. When successfully implemented, randomization allows analysts to be more confident that the empirical associations produced by the interventions are causal. The findings from this experimental literature bolster the evidence from the associational literature that we have just discussed.
Currie and Blau and Currie present comprehensive surveys of numerous preschool
26 programs and their measured effects. 47 The programs they analyze vary, both in terms of age of enrollment and age of exit. The effects, however, are generally consistent, although in some cases only weak effects are found. Generally, performance of children in school is improved in terms of less grade repetition, more graduation and higher test scores. Unfortunately, many of these programs are not evaluated by following children into late adolescence or adulthood and looking at their outcomes. Three programs have long-term follow-ups, and we focus on them here. They all target high-risk children from disadvantaged families. The Chicago Child-Parent Centers (CPC), is a half-day program on a large scale in the Chicago public schools. It is evaluated by a non- experimental method (matching) and has a sample of about 1,500 children. The second program is the Abecedarian program, a full-day, year-round educational child care program in Chapel Hill, NC. It was evaluated by randomization and has 111 participants. Students are followed to age 21. Finally, the High/Scope Perry Preschool is a small-scale half-day program in the Ypsilanti, MI public schools. It was evaluated by experimental methods. Sample size is 123, and follow-up is to age 27. CPC and Perry had a parental involvement component — Abecedarian did not. The programs differ by duration and child age of entry. Abecedarian started with young children in the first months of life. Perry and the CPC program start with older children, 3 or 4-5 years old. The programs differ in intensity. 48 It is also important to point out that the comparison made in all of the studies is between children with enriched preschool environments and children with ordinary early environments, some of whom may attend preschool and kindergarten, albeit of a less intense variety. 49
Program Descriptions 27 The Perry preschool experiment was an intensive preschool program administered to randomly selected black children enrolled in the program over five different waves between 1962 and 1967. All the children came from Ypsilanti, MI. A control group provides researchers with an appropriate benchmark to evaluate the effects of the preschool program. The assignment to the experimental group was performed in the following way. Candidate families were identified from a census of the families of the students attending the Perry school at the date of operation of the program, neighborhood group referrals and door-to- door canvassing. Poor children who scored between 75 and 85 on the Stanford-Binet IQ test were randomly divided into two undesignated groups. 50 The children were then transferred across groups to equalize the socioeconomic status, cognitive ability (as measured by the IQ test) and gender composition of the samples. Finally, a coin was tossed to determine which group received the treatment and which did not. Initially the treatment and control groups included 64 children each, but the actual treatment and control groups contained 58 and 65 children, respectively. 51
olds) and wave one (of three-year-olds) in 1962, and then waves two, three and four (of three- year-olds) entered in each subsequent year through 1965. The average age at entry was 42.3 months. With the exception of wave zero, treatment children spent two years attending the program. In the final year of the program, 11 three-year-olds who were not included in the data attended the program with the 12 4-year-olds who were. About half of the children were living with two parents. The average mother was 29 years old and completed 9.4 years of school. The treatment consisted of a daily 2 1/2 hour classroom session on weekday mornings and a weekly ninety-minute home visit by the teacher on weekday afternoons to involve the mother in the educational process. The length of each preschool year was 30 weeks, beginning in mid- October and ending in May. Ten female teachers filled the four teaching positions over the course Yüklə 3,43 Mb. Dostları ilə paylaş:
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