11

An educational study was designed to determine if having a lot of extracurricular activities (sports, choir,

orchestra, theater) in a high school reduces educational achievement by distracting students from their studies.

The researchers randomly selected 100 California high schools and then within each high school randomly

selected 200 students in each high school. For each high school they listed the number if extracurricular

activities and also the score of the students on standardized tests. To their surprise, they found that schools

with lots of extracurricular activities had much higher test scores than schools with few extracurricular activities.

Is this a designed experiment or an observational study?

Does this prove that lots of extracurricular activities is a cause of high test scores?

Can you think of a lurking variable that might affect this study?

12

In the 1950s, most Americans who drank alcohol drank either beer or hard liquor. An association of California

wine growers hired an advertising consultant named Vince Packard to run a campaign to get Americans to drink

wine. Mr. Packard ran an ad campaign conveying the idea that young, good-looking, wealthy, educated,

sophisticated people drank "dry white wine". Packard's ad agency did a survey, after the ad campaign, to

determine how effective his ad campaign had been. People who were surveyed were asked what kind of

alcoholic beverage, if any, they preferred. If they replied "a dry white wine" they were asked an additional

question: "Wine is a liquid, what does it mean to say that it is 'dry'?" Amazingly, more than half the people who

said "I like a dry white wine" had no idea what "dry" meant when applied to wine.

The people who said that they like "dry white wine" while they had no idea what a "dry wine" was were an

example of (select one):

a.

A non-representative, non-random sample.

b. The use of placebos.

c.

Too small a sample.

d. A controlled experiment (designed experiment).

e. Response bias.

13

A city government keeps track of the number of parking tickets issued each day. This is (select one):

a.

Discrete data

b. Continuous data

c.

Qualitative data

14

A survey on support for capital punishment asked the question: "Do you support capital punishment for

premeditated murder? " got 55% "yes" and 45% "no". A second survey of the same population asked the

question "If a person is convicted of premeditated murder, should they get the death penalty, life imprisonment

without the possibility of parole, or life imprisonment with the possibility of parole?" The second survey got

48% for capital punishment, 40% for life imprisonment without parole, and 12% for life imprisonment with the

possibility of parole.

The difference between the two surveys is best explained by:

a.

The first survey used a placebo.

b. The result of surveys can depend on how you word the question and what alternatives are offered.

c.

This can only be explained by a biased sample.

Required Homework 1

15

The late Harvard University paleontologist and bio-statistician Stephen J. Gould used the following example in

his class. He compared the weight of his children's pet turtle to the price (per pound) of Swiss cheese. He found

that in years when the price of Swiss cheese was high, the turtle was also larger. What can we conclude from

this? (Select one.)

a.

Time is a lurking variable. Over time, the turtle gets bigger, and the price of Swiss cheese increases due

to inflation.

b. The turtle is gaining weight because he eats too much Swiss cheese. In fact, the Gould family turtle eats

so much Swiss cheese as to create a shortage, so the price of Swiss cheese increases due to supply and

demand economic factors.

c.

The turtle gets fat because he's anxious about whether his family will be able to afford to feed him Swiss

cheese, given the price increase.

16

Which of the following is qualitative data (select one):

a.

A psychologist classifies patients by personality type.

b. A website keeps track of the number of people who visit the site each day.

c.

A veterinarian keeps track of the blood sugar of a diabetic cat.

d. A typing teacher measures the typing speed of his students in words per minute.

e. Mission College keeps records of the number of students in each class.

17

A study is designed to identify whether there is a link between drinking alcohol and breast cancer. The study

involves 300 women who have been diagnosed with breast cancer and 300 women who have not been

diagnosed with cancer. Each woman was asked how many alcoholic drinks she had per week, on the average,

during their adult years. The women with cancer reported drinking significantly more than the women who did

not have cancer.

This is a controlled experiment (designed experiment). TRUE FALSE

This is a retrospective study. TRUE FALSE

This study will probably suffer from response bias. TRUE FALSE

This is an observational study. TRUE FALSE

18

A medical study is designed to test a new drug to treat pneumonia. Patients are randomly assigned to get the

new drug or an older drug which is not completely satisfactory. After 5 days of treatment, the patients are

evaluated to see how much they have improved. The patients do not know which dug they are getting but the

doctors evaluating them do. Select one option below:

(a) This is a blind study but not a double blind study.

(b) This is a longitudinal study.

(c) This is both a blind study and a double blind study.

19

An educational study wants to evaluate the effectiveness of teaching algebra online. The population of interest

is all community colleges in California. Five California community colleges are randomly selected. At each

college, half the algebra students are randomly assigned to traditional classes and half are assigned to online

classes. And the end of the semester they all took the same final exam, and the results were compared .

This is a cluster sample. TRUE FALSE

This is an an observational study. TRUE FALSE

This is a stratified sample. TRUE FALSE