Did I Get This – Connection between Confidence Intervals and Hypothesis Tests

Published: October 22nd, 2013

Category: Activity 2: Did I Get This?

The UCLA Internet Report (February 2003) estimated that roughly 8.7% of Internet users are extremely concerned about credit card fraud when buying online. A study was designed in order to examine whether that proportion has changed since. Let p be the proportion of all Internet users who are concerned about credit card fraud. In this study we are therefore testing:

Ho: p = 0.087

Ha: p ≠ 0.087

Based on the collected data, a 95% confidence interval for p was found to be (0.08, 0.14).


The UCLA Internet Report (February 2003) estimated that roughly 60.5% of U.S. adults use the Internet at work for personal use. A follow-up study was conducted in order to explore whether that figure has changed since. Let p be the proportion of U.S. adults who use the Internet at work for personal use.

Ho: p = 0.605

Ha: p ≠ 0.605

Based on the collected data, the p-value of the test was found to be 0.001.


This document is linked from More about Hypothesis Testing.