Here is an example you can use to practice graphingand evaluating data.

An ecologist observed that sugar maples seemed to dominate the understory of a forest while the larger (older) trees were mainly white oaks. Are the maples replacing the oaks?

NULL HYPOTHESIS: There is no significant difference between the age distributions of sugar maples and white oaks in this forest.

ALTERNATIVE HYPOTHESIS: Sugar maples and white oaks in this forest have different age distributions. 

(Other alternative hypotheses are also possible.)

The ecologist counts tree rings in a sample of trees throughout the forest, and the following data are collected on tree age (in years):

Sugar maple: 2, 6, 12, 16, 18, 12, 4, 2, 18, 2, 10, 2,

4, 12, 12, 2, 4, 16, 28, 22, 26, 40, 34, 36, 38, 24, 14, 11,

13, 17, 18, 19, 12, 32, 36, 26, 30, 24, 28, 27, 28, 44, 48,

31, 34

White oak: 4, 12, 16, 10, 36, 24, 40, 22, 38, 48, 49,

60, 54, 50, 45, 49, 54, 66, 66, 74, 80, 75, 66, 62, 92, 88,

94, 94, 82, 90, 84, 90, 88, 90, 88, 91, 91, 95, 94, 116,

108, 109, 104, 106, 111, 126, 140

i) Graph the data on a sheet of graph paper (you may use Excel or PowerPoint)

ii) Describe the procedures a scientist would use to evaluate the hypothesis.

iii) Using the accepted terminology, state the conclusions of the experiment relative to the hypothesis.