Statistics: Principles and Methods, 7th Edition

3

Descriptive Study of Bivariate Data

1 Summarization of Bivariate Categorical Data

2 A Designed Experiment for Making a Comparison

3 Scatter Diagram of Bivariate Measurement Data

4 The Correlation Coefficient—A Measure of Linear Relation

5 Prediction of One Variable from Another (Linear Regression)

Ozone-Temperature Association and Air Quality

Ozone is a primary component of smog and breathing ground-level ozone can produce serious health effects. High daily ozone concentrations are associated with increases in asthma attacks and also mortality especially among the elderly. A broad segment of the population experiences respiratory problems and allergy type symptoms when temperature and ozone are both at high levels.

The Environmental Protection Agency has set safe standards and ozone alerts are issued on days when high levels of ozone are expected. During the summers of 2011 and 2012, the Wisconsin Department of Natural Resources recorded the daily maximum temperature and ozone (parts per billion) for Milwaukee County. A plot, based on the readings from 23 Wednesdays, reveals a relationship.

Days with high maximum temperature tend to have high ozone. Other days have small values of both temperature and ozone. This indicates a positive association between maximum temperature ...