STAT101 Study Guide - Scatter Plot, Cluster Sampling, X&Y

Given the following scatter diagram, the sample correlation coefficient r:

a) Has a positive linear correlation

b) Has a negative linear correlation

c) Has little or no correlation

d) Looks close to + 1.00

Application 1.3 How can we check the health of a stream?

Nitrates are organic compounds that are a main ingredient in fertilizers. When those fertilizers run off into streams, the nitrates can have a toxic effect on fish. An ecologist studying nitrate pollution in two streams measures nitrate concentrations at 42 places on Stony Brook and 42 places on Mill Brook. The parallel dotplots below display the data.

1. Explain what the dot above 12 in the Stony Brook graph represents.

2. What percent of the nitrate concentration measurements for each stream exceeded 10 mg/L?

Compare the centers of these two distributions.

The measure of the strength of the linear relationship between two variables is referred to as the:

a) Quotient of Correlation

b) Coefficient of Correlation

c)Measure of Strength

d) Lease Squares