Suppose Christiana Hospital would like to estimate the proportion of patients who feel that physicians who care for them always communicated effectively when discussing their medical care. A pilot sample of 40 patients found that 33 reported that their physician communicated effectively.

Determine the additional number of patients that need to be sampled to construct a 95% confidence interval with a margin of error equal to 3% to estimate this proportion.

Verify your result using PHStat.

AppendixLO1