# Dimitriy Masterov

Dimitriy Masterov
Research Scientist
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Biography

Dimitiy V. Masterov is an empirical micro-economist. He is keenly interested in the business potential of modern econometric methods that integrate heterogeneity, diversity, and unobserved counterfactual states.

These approaches ameliorate the problems caused by violations of standard statistical assumptions owing to the nature of economic relationships, and they facilitates the identification of true causal effects from the big data that today's companies have at their disposal. These are questions that A/B tests cannot always answer.

Publications
Proceedings of the 24th International Conference on World Wide Web, 88-96 (2015)

### Is Sniping A Problem For Online Auction Markets?

A common complaint about online auctions for consumer goods is the presence of snipers,'' who place bids in the final seconds of sequential ascending auctions with predetermined ending times. The literature conjectures that snipers are best-responding to the existence of incremental" bidders that bid up to their valuation only as they are outbid. Snipers aim to catch these incremental bidders at a price below their reserve, with no time to respond. As a consequence, these incremental bidders may experience regret when they are outbid at the last moment at a price below their reservation value. We measure the effect of this experience on a new buyer's propensity to participate in future auctions. We show the effect to be causal using a carefully selected subset of auctions from eBay.com and instrumental variables estimation strategy. Bidders respond to sniping quite strongly and are between 4 and 18 percent less likely to return to the platform.

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Proceedings of the Sixteenth ACM Conference on Economics and Computation (EC '15). ACM, New York, NY, USA (2015)

### Canary in the e-Commerce Coal Mine: Detecting and Predicting Poor Experiences Using Buyer-to-Seller Messages

Dimitriy Masterov, Uwe Mayer, Steve Tadelis

Reputation and feedback systems in online marketplaces are often biased, making it difficult to ascertain the quality of sellers. We use post-transaction, buyer-to-seller message traffic to detect signals of unsatisfactory transactions on eBay. We posit that a message sent after the item was paid for serves as a reliable indicator that the buyer may be unhappy with that purchase, particularly when the message included words associated with a negative experience. The fraction of a seller's message traffic that was negative predicts whether a buyer who transacts with this seller will stop purchasing on eBay, implying that platforms can use these messages as an additional signal of seller quality.

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Stata Journal 14 (2), 445-448 (2014)

### Review of Introduction to Time Series Using Stata by Sean Becketti

In this article, I review Introduction to Time Series Using Stata by Sean Becketti (2013 [Stata Press]).

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The Review of Agricultural Economics, 29(3):446-493. (2007)

### The Productivity Argument for Investing in Young Children

James J.Heckman

This paper presents a productivity argument for investing in disadvantaged young children. For such investment, there is no equity-efficiency tradeoff.

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In Finis Welch and Eric Hanushek, eds., Handbook on the Economics of Education, Vol. 1, Amsterdam: Elsevier, pp. 697-812. (2006)

### Interpreting the Evidence on Life Cycle Skill Formation

Flavio Cunha, James J.Heckman, Lance Lochner, Dimitriy Masterov

This paper presents economic models of child development that capture the essence of recent findings from the empirical literature on skill formation. The goal of this essay is to provide a theoretical framework for interpreting the evidence from a vast empirical literature, for guiding the next generation of empirical studies, and for formulating policy. Central to our analysis is the concept that childhood has more than one stage. We formalize the concepts of self-productivity and complementarity of human capital investments and use them to explain the evidence on skill formation. Together, they explain why skill begets skill through a multiplier process.

Skill formation is a life cycle process. It starts in the womb and goes on throughout life. Families play a role in this process that is far more important than the role of schools. There are multiple skills and multiple abilities that are important for adult success.

Abilities are both inherited and created, and the traditional debate about nature versus nurture is scientifically obsolete. Human capital investment exhibits both self-productivity and complementarity. Skill attainment at one stage of the life cycle raises skill attainment at later stages of the life cycle (self-productivity). Early investment facilitates the productivity of later investment (complementarity).

Early investments are not productive if they are not followed up by later investments (another aspect of complementarity). This complementarity explains why there is no equity-efficiency trade-off for early investment. The returns to investing early in the life cycle are high. Remediation of inadequate early investments is difficult and very costly as a consequence of both self-productivity and complementarity.

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The Journal of Law and Economics, 48(1):1-39. (2005).

### Labor Market Discrimination and Racial Differences in Premarket Factors

Pedro Carneiro, James J.Heckman, Dimitriy Masterov

We investigate the relative significance of differences in cognitive skills and discrimination in explaining racial/ethnic wage gaps. We show that cognitive test scores taken prior to entering the labor market are influenced by schooling. Adjusting the scores for racial/ethnic differences in education at the time the test is taken reduces their role in accounting for the wage gaps.

We also consider evidence on parental and child expectations about education and on stereotype-threat effects. We find both factors to be implausible alternative explanations for the gaps we observe. We argue that policies need to address the sources of early skill gaps and to seek to influence the more malleable behavioral abilities in addition to their cognitive counterparts.

Such policies are far more likely to be effective in promoting racial and ethnic equality for most groups than are additional civil rights and affirmative action policies targeted at the workplace.

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In Diane Coyle, Wendy Alexander, and Brian Ashcroft, eds., New Wealth for Old Nations: Scotland’s Economic Prospects, Princeton: Princeton University Press, pp. 119-165. (2005)

### Skill Policies for Scotland

James J.Heckman, Dimitriy Masterov

This paper argues that skill formation is a life-cycle process and develops the implications of this insight for Scottish social policy. Families are major producers of skills, and a successful policy needs to promote effective families and to supplement failing ones. We present evidence that early disadvantages produce severe later disadvantages that are hard to remedy.

We also show that cognitive ability is not the only determinant of education, labor market outcomes and pathological behavior like crime. Abilities differ in their malleability over the life-cycle, with noncognitive skills being more malleable at later ages. This has important implications for the design of policy. The gaps in skills and abilities open up early, and schooling merely widens them.

Additional university tuition subsidies or improvements in school quality are not warranted by Scottish evidence. Company sponsored job training yields a higher return for the most able and so this form of investment will exacerbate the gaps it is intended to close.

For the same reason, public job training is not likely to help adult workers whose skills are rendered obsolete by skill-biased technological change. Targeted early interventions, however, have proven to be very effective in compensating for the effect of neglect.

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in Laura B. Nielsen and Robert L. Nelson, eds., Handbook of Research on Employment Discrimination: Rights and Realities, New York: Springer. (2005)

### Understanding the Sources of Ethnic and Racial Wage Gaps and Their Implications for Policy

Pedro Carneiro, James J.Heckman, Dimitriy Masterov

Previous studies show that controlling for ability measured in the teenage years eliminates young adult wage gaps for all groups except black males, for whom the gap is reduced by approximately three-fourths. This suggests that disparity in skills, rather than the differential treatment of such skills in the market, produces racial and ethnic wage differentials.

However, minority children and their parents may have pessimistic expectations about receiving fair rewards for their skills in the labor market and so they may invest less in skill formation. Poor schools may also depress cognitive achievement, even in the absence of any discrimination.

We find that the evidence on expectations is mixed. Although all groups are quite optimistic about the future schooling outcomes of their children, minority parents and children have more pessimistic expectations about child schooling relative to white children and their parents when the children are young.

At later ages, expectations are more uniform across racial and ethnic groups. Gaps in ability across racial and ethnic groups also open up before the start of formal schooling, and the different trajectories of Hispanic and black students indicate that differences in schooling cannot be the source of cognitive disparities. Finally, test scores depend on schooling attained at the time of the test.

Adjusting for differences in schooling attainment at the age the test is taken reduces the power of measured ability to shrink wage gaps for blacks, but not for other minorities.

We also document the presence of disparities in noncognitive traits across racial and ethnic groups. These characteristics have been shown elsewhere to be important for explaining the labor market outcomes of adults. This evidence points to the importance of early (preschool) family factors and environments in explaining both cognitive and noncognitive ability differentials by ethnicity and race.

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Patents