We investigate conditions sufficient for identification of average treatment effects using instrumental variables. First we show that the existence of valid instruments is not sufficient to identify any meaningful average treatment effect. We then establish that the combination of an instrument and a condition on the relation between the instrument and the participation status is sufficient for identification of a local average treatment effect for those who can be induced to change their participation status by changing the value of the instrument. Finally we derive the probability limit of the standard IV estimator under these conditions. It is seen to be a weighted average of local average treatment effects.

Evolution and Rationality Some Recent Game-Theoretic Results. Identification and Estimation of Local Average Treatment Effects

Economists have shown that large and persistent differences in productivity levels across businesses are ubiquitous. This finding has shaped research agendas in a number of fields, including (but not limited to) macroeconomics, industrial organization, labor, and trade. This paper surveys and evaluates recent empirical work addressing the question of why businesses differ in their measured productivity levels. The causes are manifold, and differ depending on the particular setting. They include elements sourced in production practices -- and therefore over which producers have some direct control, at least in theory -- as well as from producers' external operating environments. After evaluating the current state of knowledge, I lay out what I see are the major questions that research in the area should address going forward. (JEL D24, G31, L11, M10, O30, O47)

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What Determines Productivity

机构投资者作为证券市场中的重要力量,越来越受到理论界和实务界的关注。论文对宾夕法尼亚大学沃顿商学院会计学教授布赖恩-布希（Brian Bushee）的论文＂The influence of institutional investors on myopic R＆D investment behavior＂（机构投资者对企业短视研发投资行为的影响,以下简称Bushee（1998））进行评价并提出相关的建议和研究方向。

《The influence of institutional investors on myopic R＆D investment behavior》述评

Many financial markets are characterized by strong relationships and networks, rather than arm’s-length, spot market transactions. We examine the performance consequences of this organizational structure in the context of relationships established when VCs syndicate portfolio company investments. We find that better-networked VC firms experience significantly better fund performance, as measured by the proportion of investments that are successfully exited through an IPO or a sale to another company. Similarly, the portfolio companies of better-networked VCs are significantly more likely to survive to subsequent financing and eventual exit. We also provide initial evidence on the evolution of VC networks. NETWORKS ARE WIDESPREAD IN MANY FINANCIAL MARKETS. Bulge-bracket investment banks, for instance, make use of strong relationships with institutional investors when pricing and distributing corporate securities (Cornelli and Goldreich (2001)). In the corporate loan market, banks often prefer syndicating loans with other banks over being the sole lender. Similarly, in the primary equity and bond markets, banks tend to co-underwrite securities offerings with banks with which they have longstanding relationships (Ljungqvist, Marston, and Wilhelm (2005)). Networks also feature prominently in the venture capital (VC) industry. VCs tend to syndicate their investments with other VCs, rather than investing alone (Lerner (1994a)). They are thus bound by their current and past investments into webs of relationships with other VCs. Once they have invested in a company, VCs draw on their networks of service providers—head hunters, patent lawyers, investment bankers, etc.—to help the company succeed (Gorman and Sahlman (1989), and Sahlman (1990)). Indeed, one prominent VC goes as far

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Whom You Know Matters: Venture Capital Networks and Investment Performance

Evidence on the "funding gap" for investment innovation is surveyed. The focus is on financial market reasons for underinvestment that exist even when externality-induced underinvestment is absent. We conclude that while small and new innovative firms experience high costs of capital that are only partly mitigated by the presence of venture capital, the evidence for high costs of R&D capital for large firms is mixed. Nevertheless, large established firms do appear to prefer internal funds for financing such investments and they manage their cash flow to ensure this. Evidence shows that there are limits to venture capital as a solution to the funding gap, especially in countries where public equity markets for VC exit are not highly developed. We conclude by suggesting areas for further research.

The Financing of R&D and Innovation

I find that companies funded by more experienced VCs are more likely to go public. This follows both from the direct influence of more experienced VCs and from sorting in the market, which leads experienced VCs to invest in better companies. Sorting creates an endogeneity problem, but a structural model based on a two-sided matching model is able to exploit the characteristics of the other agents in the market to separately identify and estimate influence and sorting. Both effects are found to be significant, with sorting almost twice as important as influence for the difference in IPO rates.

How Smart Is Smart Money? A Two‐Sided Matching Model of Venture Capital

We study the characteristics and abilities of CEO candidates for companies involved in buyout (LBO) and venture capital (VC) transactions and relate them to hiring decisions, investment decisions, and company performance. Candidates are assessed on more than thirty individual abilities. The abilities are highly correlated; a factor analysis suggests there are two primary factors with intuitive characterizations -- one for general ability and one that contrasts team-related, interpersonal skills with execution skills. Both LBO and VC firms are more likely to hire and invest in CEOs with greater general abilities, both execution- and team-related. Success, however, is more strongly related to execution skills than to team-related skills. Success is, at best, only marginally related to incumbency, holding observable talent and ability constant.

Which CEO Characteristics and Abilities Matter

We exploit a unique data set to study individual characteristics of CEO candidates for companies involved in buyout and venture capital transactions and relate these characteristics to subsequent corporate performance. CEO candidates vary along two primary dimensions: one that captures general ability and another that contrasts communication and interpersonal skills with execution skills. We find that subsequent performance is positively related to general ability and execution skills. The findings expand our view of CEO characteristics and types relative to previous studies.

/pdf/which-ceo-characteristics-and-abilities-matter-2nmr77nj7x.pdf

I find that companies funded by more experienced VCs are more likely to go public. This follows both from the direct influence of more experienced VCs and from sorting in the market, which leads experienced VCs to invest in better companies. Sorting creates an endogeneity problem, but a structural model based on a Two-Sided Matching model is able to exploit the characteristics of the other agents in the market to separately identify and estimate influence and sorting. Both effects are found to be significant, but sorting is almost twice as important as influence for the difference in IPO rates.

https://papers.ssrn.com/sol3/Delivery.cfm/SSRN_ID878692_code502093.pdf?abstractid=878692&mirid=1

How Smart is Smart Money? A Two-Sided Matching Model of Venture Capital

A long-standing controversy is whether LBOs relieve managers from short-term pressures from public shareholders, or whether LBO funds themselves are driven by short-term profit motives and sacrifice long-term growth to boost short-term performance We investigate 495 transactions with a focus on one form of long-term activities, namely investments in innovation as measured by patenting activity We find no evidence that LBOs are associated with a decrease in these activities Relying on standard measures of patent quality, we find that patents granted to firms involved in private equity trans actions are more cited (a proxy for economic importance), show no significant shifts in the fundamental nature of the research, and are more concentrated in the most important and prominent areas of companies' innovative portfolios

Morten Sorensen

Papers

How Smart Is Smart Money? A Two‐Sided Matching Model of Venture Capital

Which CEO Characteristics and Abilities Matter

Which CEO Characteristics and Abilities Matter

How Smart is Smart Money? A Two-Sided Matching Model of Venture Capital

Private Equity and Long-Run Investment: The Case of Innovation