What does the evidence show on preschool?

A recent article by Professor David Armor repeats many of the common arguments made by researchers opposed to current proposals for expanding preschool.  The article was published online by the Cato Institute, a libertarian think tank.

The article’s arguments have been frequently made by opponents of universal preschool. In particular, these arguments are similar to those made by Russ Whitehurst of the Brookings Institution, who has previously co-authored a blog post on preschool research with Professor Armor.

The argument in brief is as follows. First, these critics admit that the Perry and Abecedarian experiments provide evidence for the long-term benefits of these preschool programs, but this evidence is argued to be irrelevant to current preschool proposals. Second, the many “regression discontinuity” studies that show strong effects of many current preschool programs on kindergarten entrance test scores are argued to be biased.  Third, the Head Start and Tennessee experiments are argued to show that the effects of current preschool programs are likely to quickly fade.

I have already responded to these arguments in the past. For a more academic take on the research evidence, see my blog post responding to Whitehurst’s weighting of the research evidence, and explaining how I weight the evidence. For a more accessible discussion aimed at a broad audience, see chapter 4 of my new book, From Preschool to Prosperity, and also endnote 21 in that book.

Let me emphasize here just a few points.

First, regarding the Perry and Abecedarian experiments, these critics argue that the strong benefits of these programs are irrelevant to the current policy debate because the Perry and Abecedarian programs are more expensive per child than most current preschool programs. But why do these critics mainly use this argument as a reason to oppose current preschool programs?  If the critics accept that these more expensive preschool programs have high benefit-cost ratios, they should be arguing for spending more per child on highly-intensive preschool programs. Rather than an argument for doing nothing, the Perry and Abecedarian programs provide an argument for doing more.

Furthermore, the argument for today’s preschool programs is not that they will fully replicate the very large benefits of the Perry and Abecedarian programs. Rather, the argument is that at a lesser cost, current preschool programs will still provide a high benefit-cost ratio. As reviewed in my new book, Perry is estimated to increase adult earnings by 19% and the Abecedarian program by 26%. Most current preschool programs are estimated to increase adult earnings by 5 or 10%, but at a much lower cost. A full-day program with similar effectiveness to Tulsa’s preschool program is estimated to increase adult earnings by around 10%, but at a sufficiently lower cost that its benefit-cost ratio is somewhat higher than that of the Abecedarian program (see chapter 3 of my new book).

Second, regarding the “regression discontinuity design” (RDD) studies, Armor and other critics argue that these studies are biased by attrition from the treatment group. “Regression discontinuity” studies look at test scores at pre-K entrance, and at kindergarten entrance for children who attended pre-K the previous year. The studies than estimate how much of the increase in test scores for the latter group is due to the one year of aging, and how much is due to the pre-K program. This separation is done by looking at how test scores vary with age in both the pre-K entrant group and the kindergarten entrant group.

Armor’s point is that the “treatment group” of kindergarten entrants may miss some children who dropped out of preschool or who left the school district. This point is true. Armor argues that the omitted children will have lower test scores, which, if true, would bias the RDD results towards finding larger effects of pre-K. This argument, however, is by no means obvious. For example, in these studies of urban school districts, more upwardly mobile families who move to the suburbs are less likely to be in the kindergarten entrant group, and these children would probably tend to have above average test scores.

But Armor’s argument of bias in RDD estimates overlooks two important points. One point is that even when we redo regression discontinuity studies and only include children observed at both pre-K entrance and kindergarten entrance, we get similar estimated effects. This is shown in a study I did of a Kalamazoo pre-K program. Although attrition in principle might bias RDD estimates of preschool’s benefits, in practice attrition doesn’t seem to make much difference.

A second point is that the observed pattern of results in RDD studies of pre-K is inconsistent with attrition bias explaining these results. In Tulsa, the estimated RDD effects on test scores imply that half-day pre-K increases adult earnings by about 6%, and that full-day pre-K increases adult earnings by about 10%. (See p. 48 of my new book.)This pattern of effects is quite reasonable – one would expect full-day pre-K to have larger effects than half-day pre-K, but perhaps not twice as high effects due to some diminishing returns. But there is no reason that attrition bias should result in this pattern of effects. Why would attrition bias lead to a higher positive bias for full-day pre-K students than for half-day pre-K students?  There is no reason for this pattern to occur for attrition bias.

Third, Armor argues that the Head Start results imply that Head Start has no lasting effects compared to no preschool at all. This argument is based on a reanalysis of the Head Start results in a dissertation by Peter Bernardy, a former student of Armor’s. I’ve read Dr. Bernardy’s dissertation. In the dissertation, he does a non-experimental match of Head Start participants in the Head Start treatment group to children in the control group who attended no preschool.

Although Dr. Bernardy’s results are interesting, they are potentially subject to serious selection bias. As researchers know, the problem in evaluating preschool, or any educational or social intervention, is that there are unobserved pre-existing differences between program participants and non-participants that we can’t control for, because by definition we don’t observe these differences. Preschool families may be either more ambitious or needier than non-preschool families in ways we don’t observe, which will bias comparisons of preschool participants versus non-participants. The post-preschool differences between the two groups could be due to preschool, or could be due to the pre-existing differences.

The ideal solution to this selection bias problem is a randomized control trial. This is the “gold standard” for overcoming selection bias. If preschool participants are selected randomly, and the sample size is large enough, we have a reasonable expectation that the preschool participants and non-participants will be effectively the same on average in unobserved pre-existing characteristics.

Another good solution to the selection bias problem is some “natural experiment”, where preschool access varies with some factor that is arguably unrelated to unobserved characteristics. These natural experiments provide a “silver standard” for dealing with selection bias. For example, the RDD studies of preschool are really natural experiments, because the timing of pre-K access varies with age. Both the treatment group (kindergarten entrants who were in pre-K the previous year), and the control group (pre-K entrants) were similarly selected into preschool.

A less satisfactory solution to the problem of selection bias due to unobserved characteristics is to statistically control for observed characteristics. This is a “bronze standard” for dealing with selection bias. We may hope that by controlling for observed characteristics, we may also reduce differences in unobserved characteristics. But it is impossible to tell if this is so, and in practice, we know from many previous studies that “bronze standard” studies of program effectiveness have often proved misleading.

As Dr. Bernardy appropriately acknowledges in his dissertation, his estimates of the effects of Head Start vs. no-preschool may be biased by unobserved family and child characteristics.   (p. 89-90:  “It should be acknowledged that the omission of unobserved characteristics could lead to bias in the resulting estimation. For instance, varying levels of motivation among children’s parents that is not captured by the included covariates could yield a biased result.”) What direction or size might this bias have? We have no idea.

Professor Armor, along with Dr. Whitehurst and other critics of preschool, usually puts a heavy emphasis on “gold standard” results from randomized control trials. It is therefore odd that so much emphasis is placed in Professor Armor’s paper on Head Start results that are not based on a random experiment, or even on a natural experiment.

What is a non-researcher to make of all this debate over what studies to believe? A natural reaction is to say “we just don’t know anything”. This then argues for the need for more research before going forward with any ambitious preschool plan.

But what should be kept in mind is that Professor Armor and Dr. Whitehurst are distinctly in the minority of researchers in their interpretation of the overall research evidence. The research consensus is much more represented by a report in 2013 by ten of the most distinguished early childhood researchers, Investing in our future: The evidence base on preschool education. This research consensus finds, quoting from the main conclusions of the Executive Summary, that:

“Large-scale public preschool programs can have substantial impacts on children’s early learning….Quality preschool education is a profitable investment… Quality preschool education can benefit middle-class children as well as disadvantaged children… Long-term benefits occur despite convergence of test scores.”

Marketing doubt is easier than moving forward. But what must be always kept in mind is that there are costs not only to moving forward, but also to doing nothing. Children are only age 4 once. If we fail to provide preschool that could positively affect a child’s life course, that opportunity is lost forever. We can of course intervene later, but the main consensus conclusion from the early childhood research literature is that early interventions at ages 3 and 4 can have a particularly high benefit-cost ratio and can reach more children.

There are risks to moving forward. There are risks to doing nothing. Overall, the research consensus is that high-quality preschool has much higher benefits than costs. These benefits occur not only for the participating children and families, but for our overall economy and society.

Posted in Early childhood programs | 2 Comments

Early childhood education is a good we know how to do

In my new book, From Preschool to Prosperity, I put early childhood education in the context of other efforts to increase high-wage employment. Early childhood education is by no means the only policy needed as part of a comprehensive strategy to advance broader economic opportunity.

Early childhood education is but one strategy to improve the quality of the American labor supply. Improving the quality of the American labor supply helps increase wages by creating an economic environment in which firms can readily find skilled labor and therefore are able to implement new technologies and improve productivity. In addition to improving ECE, policymakers need to improve the quality of K-12 education, and to make postsecondary education more financially easy to access.

Labor demand policies are also needed to directly encourage businesses to expand the number of high-wage jobs. Such policies could include manufacturing extension services, which help small and medium sized manufacturers to improve their productivity and competitiveness. Customized job training programs can help encourage businesses to expand high-wage jobs by directly providing the needed skills for specific jobs. Tax policies that reward job creation can also be used to encourage the expansion of high-wage jobs.

However, of all these various labor supply and demand policies, early childhood education probably has the most extensive and rigorous evidence for its effectiveness at a large scale. Our knowledge is not perfect, but is more than adequate to justify large scale investment. Early childhood education represents a good we know how to do.

Posted in Economic development

Why early childhood education now?

As argued in my new book, From Preschool to Prosperity, expanded early childhood education represents a continuation of the American historical tradition of promoting economic opportunity and growth via expanded education. But why is there a need for early childhood education now, when apparently we did not perceive a need for such programs in the past?

First, the American economy has changed so as to put a much greater premium on higher skills. Higher wages require higher skills to a much greater extent than was true in the past. This puts pressure on policymakers to figure out as many ways as possible to improve skills, including but not restricted to early childhood education.

Second, we now understand to a greater extent the importance of early learning. It is now clear that what happens in the years from birth to age five are critical to setting the stage for later learning. This was not fully appreciated in the past.

Third, American families are now under more economic and social stress than they were in the past. Many more families need to put younger children in child care and pre-K so that parents can work. If children are in child care and pre-K settings, it makes sense to try to make those settings as high-quality as possible in promoting long-run development.

The world has changed, our scientific understanding has changed, and our families have changed. All these changes mean that broadening access to high-quality early childhood education is a needed initiative to meet the challenges of our times.

Posted in Economic development

Early childhood education is a continuation of an American tradition of promoting economic growth through education

In my new book, From Preschool to Prosperity, I put early childhood education in a historical context. The U.S. has long seen expanded education as a key to promoting a better economy.

The U.S. was a leader in expanding free public education. The “common school movement” of the 19th century advocated free public education through 8th grade. The “high school movement” of the late 19th and early 20th century expanded education access through 12th grade.

These initiatives were explicitly rationalized as a way to promote greater economic opportunity for all. For example, one of the leaders of the common school movement, Horace Mann, argued the following in 1848:

Nothing but universal education can counterwork [the] tendency to the domination of capital and the servility of labor. . . . If education be equally diffused, it will draw property after it by the strongest of all attractions, for such a thing never did happen, and never can happen, as that an intelligent and practical body of men should be permanently poor.

The economic development argument for promoting early childhood education is therefore not a new argument. In fact, today we have more rigorous social science evidence for expanding preschool than the common school movement and the high school movement had for expanding K-12 education. Horace Mann and the other school reformers of the 19th century were operating more on the basis of anecdote, casual observation, and instinct than on what would today be regarded as rigorous scientific evidence. Yet who can doubt that America is a far different and far better country because of our past historical commitments to free public education? Early childhood education today represents a continuation of that past progress.

Posted in Economic development

Increasing quality in preschool through accountability and mentoring

One important issue discussed in my new book, From Preschool to Prosperity, is what can be done by government to increase the quality of local pre-K programs. Although there is good evidence that a wide variety of state and local agencies can successfully implement quality pre-K programs, there is no guarantee that any particular local program will be high-quality. Regardless of whether state governments or the federal government finance pre-K, there will be some demand for accountability for results.

For pre-K, federal and state governments should resist the pressure to over-emphasize standardized tests in evaluating individual pre-K providers. I believe that there should be regular monitoring using tests of whether the overall state or federal pre-K program is improving kindergarten readiness. This can be done through comparing test scores at pre-K entrance and kindergarten entrance, and adjusting for the improvements that are due to aging alone, without pre-K, by using the range in test scores with age among each group of children. (Technically, this is referred to as doing a “regression discontinuity” study of pre-K, where we see how test scores vary with age, and then see what “jump” there is at kindergarten entrance.)

Such an evaluation of the overall program answers the important question: is this program improving overall kindergarten readiness? However, state or federal agencies overseeing pre-K funding should resist using measures of test score gains at kindergarten entrance to evaluate individual agencies, for several reasons.

The most important reason for being wary of standardized-test based accountability of individual pre-K agencies is that such a system would put enormous pressure on individual agencies to aim at maximizing the performance of 4-year-olds on standardized tests that examine cognitive skills. While cognitive skills are important, pre-K should also be aiming at improving social skills and character skills, which are hard to measure using standardized tests. Narrowing pre-K to a cognitive skills-only approach is undesirable.

For individual agencies, one approach to accountability is to use measures of classroom quality derived from the observations of trained outside observers, for example the CLASS measure of pre-K classroom quality. These measures have trained observers come in and periodically rate in a reasonably objective fashion various features of how children are interacting with each other and with the teacher. In the case of CLASS, there is some evidence that this measure is correlated with later test scores gain.

However, the CLASS measure has the significant advantage in that in looks at both quality features related to cognitive skills and quality features related to social and character skills. For example, the CLASS measure includes some measures of whether the classroom climate is positive.

The CLASS measure also has the advantage of providing useful feedback to individual programs and classroom teachers. Test-based accountability measures are more of a black box. It is difficult to use standardized test results to figure out how to improve program quality.

Observational classroom measures might be complemented by teacher mentoring/coaching approaches. Experienced, high-quality pre-K teachers might add their observations of individual classrooms, and meet with the class’s teacher to make suggestions for how the class’s quality could be improved.

Accountability is a legitimate demand of taxpayers. Quality is essential for pre-K programs to have high benefit-cost ratios. The challenge is developing a clear-cut accountability and quality improvement system that doesn’t encourage strategic behavior to maximize some test score, and that truly provides assistance that makes a difference to quality. Classroom-based observations coupled with follow-up by teacher mentors seems a reasonable approach to try. As we gain experience, we should be able to improve the usefulness and reliability of these classroom-based observations, and be able to focus the teacher mentoring on the most important elements of quality.

Posted in Early childhood program design issues | 3 Comments

Should early childhood education be financed by state governments, the federal government, or both?

One important governance issue discussed in my new book, From Preschool to Prosperity, is whether pre-K and other early childhood programs should be primarily financed by state governments or the federal government.

I’m a political pragmatist. I think either approach can work. What will prove to be politically feasible is hard to predict. However, I think that for preschool, there are advantages to state governments playing a leading role, with some federal support. In contrast, I suspect that any full-scale commitment to child care and parenting programs will require more federal involvement.

As discussed in the book, and in a previous blog post, the evidence suggests that pre-K provides broad benefits, with pre-K programs not only improving the future prospects of low-income children, but also helping children from middle-class families. These broad benefits provide a rationale for universal pre-K programs.

Universal pre-K programs are likely to attract broad voter support, particularly once they are in place. Therefore, I think it is certainly politically feasible for state governments to decide to operate universal pre-K programs, and some state governments, for example Oklahoma, have done so.

The cost of universal pre-K also seems feasible for state and local governments to finance. I estimate the additional costs of universal pre-K at around $25 billion annually. While this is a lot of money, the figure must be put in the context of the large size of the U.S. economy and of government operations. This $25 billion amounts to 1.75% of overall state and local taxes, and 4% of what we currently spend on K-12 education.

The federal government could also finance universal pre-K. However, the federal government already has a lot on its plate in dealing with the implementation of health reform, and dealing with the growing needs of an aging population. There is some wisdom in focusing federal attention where state and local governments are much less likely to do a good job.

In addition, although we know quality pre-K works, there is still uncertainty over what program designs work the best, for example in terms of what curriculum is the best and what teacher training approach is the best. This argues for allowing for considerable state and local flexibility in program design, to allow for innovation. Such flexibility may be somewhat easier with state financing than with federal financing.

However, if we want to learn from such innovation, federal involvement in funding evaluation of state and local pre-K programs would be quite helpful. The benefits of pre-K program evaluation accrue to programs everywhere, not just in the state in which the program being evaluated is located. These external benefits of evaluation imply that states on their own will tend to underfund evaluation studies, which can be corrected with federal funding of high-quality evaluations.

A similar argument supports federal funding for evaluation of alternative pre-K curriculums. The entire nation benefits from learning, for example, whether the Boston pre-K program’s use of the Building Blocks curriculum helps explain its unusually large test score effects.

Federal funding might also be quite helpful in supporting teacher mentoring and training. Underinvesting in quality can be politically tempting for state governments facing fiscal challenges. Some extra federal funds to support quality initiatives would help overcome this temptation.

For child care programs that operate in early childhood, such as Educare, federal financial support is likely to be necessary for these programs to operate at anything close to full-scale. As discussed in the book and previous blog posts, the evidence is that high-quality child care provides much greater benefits to low-income children than middle-income children. Therefore, research supports targeting such child care subsidies on low-income families.

These quality early child care programs are quite expensive, costing $16,000 per year for five years during early childhood. To operate at a full-scale that serves all disadvantaged children would cost over $50 billion per year. This cost is about 4% of state and local taxes.

It is politically difficult for state and local governments to generate political support for a program that requires a 4% tax increase for state and local voters, but then all the direct benefits go to disadvantaged families. As argued in the book and in previous blog posts, there are spillover benefits of such programs for everyone in society. However, the tax increase is still a tough initiative to sell to many state and local voters.

At the federal level, the interests of the poor tend historically to have had somewhat greater political clout (although hardly overwhelming clout) than at the state and local level. The federal government also has somewhat higher revenue-raising capacity as well.

Parenting/home visiting programs such as the Nurse Family Partnership also tend to have benefits only for lower-income families. This also argues for the need for federal support. On the other hand, these programs are considerably cheaper than free child care from birth to age 5. A full-scale NFP offering services to all first-time disadvantaged mothers would probably cost about $4 billion per year nationally. This cost is less than one-half of 1% of state and local taxes, so this seems more feasible for a sizable state and local involvement.

Full-scale implementation of a package of early childhood education programs seems more likely if we elicit the support of all levels of government. If each level of government focuses on areas where it has a comparative advantage, we are more likely to achieve a full-scale program package that is economically and politically sustainable.

Posted in Early childhood program design issues, National vs. state vs. local

What are the costs of a full-scale commitment to early childhood education?

In my new book, From Preschool to Prosperity, I outline a specific proposal, backed by research, for a full-scale early childhood program. This program consists of three components: (1) universal full-day pre-K for all 4-year olds; (2) income-targeted full-time, full-year child care and pre-K from birth to age 5 for all disadvantaged children, similar to today’s Educare program; (3) income-targeted Nurse Family Partnership home-visiting/parenting services for all first-time disadvantaged mothers.

After allowing for pre-K and child care services we are already providing through the federal government and state governments, the net annual cost of each of these components would be: (1) universal pre-K, $25 billion per year; (2) targeted child-care, birth to age 5, $58 billion per year; (3) NFP, $4 billion per year. Although these numbers add up to $87 billion, there is some overlap if all three components were funded, for example the pre-K at age 4 for disadvantaged children is part of both component (1) and component (2). Adjusting for this overlap, the net cost of the entire package would be $79 billion.

$79 billion is obviously a lot of money. But the amount represents only 2 percent of total federal, state and local taxes. Alternatively, this amount represents about 13 percent of what is currently spent on public K-12 education. Therefore, this $79 billion in annual spending represents a considerable but not outlandish increase in our investment in education, at a tax cost that is a modest increase in the overall tax burden.

The costs of this $79 billion in annual investment would be considerably outweighed by the benefits. This proposal would annually provide pre-K to 3 million 4-year-olds, and child care services to an additional 3 million children ages 0-3, along with NFP services to about 1 million families. The future earnings benefits for former child participants would have a present value of between 2 and 3 times the costs of this investment, so the package would be worthwhile for these direct benefits alone. Earnings benefits for parents from the free child care and the home-visiting services would by itself have a present value of about one-and-a-half times this investment, so the package would even be worthwhile if there were no benefits for child participants. Finally, the evidence suggests that the spillover benefits of the greater skills of former child participants and their parents on the wages of other workers would more than double overall benefits, as argued in a previous blog post. Overall, the package’s benefits should exceed 10 times its annual costs, simply in terms of increased earnings for the economy. And this does not count any benefits from reduced crime, which would be quite likely to be large.

Early childhood education at full-scale is not cheap, but is affordable. Among policy alternatives for boosting the long-run growth of the economy, early childhood education has some of the best evidence of high benefit-cost ratios that more than justify full-scale investment.

Posted in Early childhood program design issues