Question

CS1173 HWP4: Histograms and errorbars Name 1: _________________________

Name 2: _________________________

This worksheet is done in pairs. After you are checked off you can leave or work on assignments.

1) A scientist measures performance on a PVT (psychomotor vigilance task) in which the subject is supposed to push a button each time a light appears on the screen. The number of times the subject misses is a good measure of sleepiness. Twelve subjects perform this task and have lapses of 1, 1, 5, 3, 10, 2, 5, 5, 8, 2, 5, 1, respectively.

a) Fill in the frequency table:

b) In the graph to the right, draw the histogram of this data. Label the data carefully.

c) The data was taken in the morning after the subjects had gotten 8 hours of sleep. The average number of lapses was 4 and the standard deviation of the data was 2.77. What percentage of the data falls in the SD error bars? (Actually calculate it. Show your work.) Does this agree with rule of thumb of 68% if the data is normally distributed? Why or why not?

Answer 1