Acid rain Biologists studying the effects of acid rain on wildlife collected data from 163 streams in the Adirondack Mountains. They recorded the pH (acidity) of the water and the BCI, a measure of biological diversity, and they calculated R2 = 27,. Heres a scatterplot of BCI against pH: a) What is the correlation between pH and BCI? b) Describe the association between these two variables. c) If a stream has average pH, what would you predict about the BCI? d) In a stream where the pH is 3 standard deviations above average, what would you predict about the BCI?

Statistics Week 4 Aids to the Interpretation of Box Plots 1. The line (median) inside the box represents the “center” of the distribution of data. S= {1, 3, 5, 6, 10, 12, 68} Median: 6 Q U : 12 QL : 3 *IQR= Inner Quartile Range= QU−Q L 2. Examine the length of the box. The IQR is a measure of the sample’s variability and is especially useful for the comparison of two samples. 3. Visually compare the lengths of the whiskers. If one is clearly longer, the distribution of the data set is probably skewed in the direction of the longer whisker (top longer- right skew; bottom longer-left skew). 4. Analyze any measurements that lie beyond the fences. Example: Mean= $64,000