Skip to main content Accessibility help
×
Hostname: page-component-7c8c6479df-8mjnm Total loading time: 0 Render date: 2024-03-18T19:07:44.097Z Has data issue: false hasContentIssue false

13 - Estimating the Propensity Score

from PART III - REGULAR ASSIGNMENT MECHANISMS: DESIGN

Published online by Cambridge University Press:  05 May 2015

Guido W. Imbens
Affiliation:
Stanford University, California
Donald B. Rubin
Affiliation:
Harvard University, Massachusetts
Get access

Summary

INTRODUCTION

Many of the procedures for estimating and assessing causal effects under unconfoundedness involve the propensity score. In practice it is rare that we know the propensity score a priori in settings other than those involving randomized experiments. Such practical settings could have complex designs where the unit-level probabilities differ in known ways. An example is the allocation of admissions to students applying for medical school in The Netherlands in the 1980s and 1990s. Based on high school grades, applicants would be assigned a priority score that determined their probability of getting admitted to medical school. The actual admission to medical school was then based on a (random) lottery. Such settings are rare, however, and a more common situation is where, given the pre-treatment variables available, a researcher views unconfoundedness as a reasonable approximation to the actual assignment mechanism, with only vague a priori information about the form of the dependence of the propensity score on the observed pre-treatment variables. For example, in many medical settings, decisions are based on a set of clinically relevant patient characteristics observed by doctors and entered in patients’ medical records. However, there is typically no explicit rule that requires physicians to choose a specific treatment based on particular values of the pre-treatment variables. In light of this degree of physician discretion, there is no explicitly known form for the propensity score. In such cases, for at least some of the methods for estimating and assessing treatment effects discussed in this part of the book, the researcher needs to estimate the propensity score. In this chapter we discuss some specific methods for doing so.

It is important to note that the various methods that will be discussed in the chapters following this one, specifically Chapters 14–17, use the propensity score in different ways. Some of these methods rely more heavily than others on an accurate approximation of the true propensity score by the estimated propensity score.

Type
Chapter
Information
Publisher: Cambridge University Press
Print publication year: 2015

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Save book to Kindle

To save this book to your Kindle, first ensure coreplatform@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.

Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Save book to Dropbox

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.

Available formats
×

Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

Available formats
×