The data come from the Hospital Compare web site (http://hospitalcompare.hhs.gov)
run by the U.S. Department of Health and Human Services. The purpose of the web site is to provide data and
information about the quality of care at over 4,000 Medicare-certied hospitals in the U.S. This dataset es-
sentially covers all major U.S. hospitals. This dataset is used for a variety of purposes, including determining
whether hospitals should be ned for not providing high quality care to patients (see http://goo.gl/jAXFX
for some background on this particular topic).
The Hospital Compare web site contains a lot of data and we will only look at a small subset for this
assignment. The zip le for this assignment contains three les
? outcome-of-care-measures.csv: Contains information about 30-day mortality and readmission rates
for heart attacks, heart failure, and pneumonia for over 4,000 hospitals.
? hospital-data.csv: Contains information about each hospital.
? Hospital_Revised_Flatfiles.pdf: Descriptions of the variables in each file

1 Plot the 30-day mortality rates for heart attack
Read the outcome data into R via the read.csv function and look at the rst few rows.

> outcome <- read.csv("outcome-of-care-measures.csv", colClasses = "character")
> head(outcome)

Case study: 用R统计分析医院疾病相关数据