August 22, 2012
Activity 1.2 - "See No Evil, Hear No Evil?"
August 22, 2012
Activity 1.2 - "See No Evil, Hear No Evil?"
August 22, 2012
Statistical problem-solving process
I. Ask a question of interest.
A statistics question involves some characteristic that
varies from individual to individual.
II. Produce data.
The methods of choice are observational studies and
experiments.
III. Analyze data.
Graphs and numerical summaries are the tools for
describing patterns in the data, as well as any
deviations from those patterns.
IV. Interpret results
The results of the data analysis should help answer
the question of interest.
August 22, 2012
What is “Normal” Body Temperature?
If a thermometer under your tongue reads higher than 98.6°F, do you have a fever? Maybe not. People
vary in their “normal” temperature. Your own temperature also varies—it is lower around 6 A.M. and
higher around 6 P.M.
Researchers designed an observational study to investigate the long-accepted value of 98.6°F, which was
established in 1878 by German doctor Carl Wunderlich. In the study, 148 healthy men and women aged 18
to 40 had their temperatures taken orally several times over a three-day period. A total of 700 temperature
readings were produced.
When researchers published their results, they did not provide the original data. This is unfortunately a
common practice. By working backward from graphs and numerical information given in the article,
however, Allen Shoemaker from Calvin College produced a data set with many of the same characteristics
as the original temperature readings.
QUESTIONS
1. Explain why this is an observational study and not an experiment.
2. To what population does the conclusion about normal body temperature apply? Justify your answer.
3. A dotplot of Shoemaker’s temperature data is shown below. We have added a vertical line at 98.6°F
for reference. What does this graph tell you about “normal” body temperature?
August 22, 2012
What is “Normal” Body Temperature?
4. How do male and female temperatures compare? The dotplot below shows body
temperature readings by gender. Write a few sentences comparing normal body
temperatures for males and females in the study.
5. List and describe as many possible sources of variation in this study as you can.
The average of the 700 temperature readings was 98.2°F. For the men in the study, the average
temperature reading was 98.1°F. For the women in the study, the average temperature reading was
98.4°F. Only 8% of the temperatures recorded were equal to 98.6 degrees.
Researchers used a statistical test to determine that an average temperature of 98.2°F in
the sample of 700 measurements was extremely unlikely if the true average temperature in the
population was 98.6°F. They concluded that Carl Wunderlich’s value of 98.6°F is not a reasonable
value for “normal” body temperature.
August 22, 2012
Dot Plots on the Calculator (if time)
1) Open a new Lists & Spreadsheets Page
2) Enter Data, making sure you name your
columns in the first row (leave the formula cell
with the "diamond" blank in each column of data)
3) Open a new Data & Statistics Page
4) Click on the horizontal axis and pick which data
you want viewed as a dot plot
August 22, 2012