---
title: "About the Survey"
description: "Results for this survey are based on telephone interviews conducted under the direction of Princeton Survey Research Associates International among a nationwide sample of 1,508 adults, 18 years of age or older, from February 20-24, 2008. The following table shows the error attributable to sampling that would be expected at the 95% level of confidence […]"
date: "2008-03-19"
authors:
  - name: "Seth Rubenstein"
url: "https://www.pewresearch.org/politics/2008/03/19/about-the-survey-410/"
categories:
  - "Federal Government"
  - "Health Care"
  - "Health Policy"
  - "Medicine & Health"
  - "Military & Veterans"
  - "Military & Veterans"
  - "Military & Veterans"
---

# About the Survey

Results for this survey are based on telephone interviews conducted under the direction of Princeton Survey Research Associates International among a nationwide sample of 1,508 adults, 18 years of age or older, from February 20-24, 2008. The following table shows the error attributable to sampling that would be expected at the 95% level of confidence for different groups in the survey:

![](https://assets.pewresearch.org/wp-content/uploads/sites/5/legacy/404-4.gif)

In addition to sampling error, one should bear in mind that question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of opinion polls.