The document discusses calculating confidence limits and performing tests of significance when analyzing sample data. It provides an example of calculating a 95% confidence interval for the mean length of pebbles on a beach based on a random sample of 100 pebbles. The document then explains that tests of significance are used to determine whether differences between two or more sample data sets are statistically significant or could be due to chance. An example is given comparing temperatures measured on north and south facing slopes. Homework involves defining correlation, positive and negative correlation, and Spearman's rank correlation coefficient.

1. Starter. Calculate the standard deviation for the following data set.

2. Monthly average Temperatures. 8 12 12 11 20 10 25 9 28 8 20 7 16 6 15 5 10 4 6 3 5 2 5 1 Temperature in degrees C Month

11. Standard deviation Mean length Random sample 10 26 100 10 82 100 10 66 100 10 42 100