Exam 7: Data for Decisions

In an experiment, an observed effect is called statistically significant if:

Nonresponse occurs when:

In a medical study that is double-blind, participants do not know whether they are taking the experimental drug. This is to avoid:

A poll of 60 students selected at random at State University found that 12 were in favor of higher parking fees to support extra police patrols of parking lots on campus. In this example, the sample proportion is:

One July, the city council of a small town decides to impose an experimental curfew on all residents younger than 18 years to cut down on loitering in the town square. After four months, the number of teens found in the square after dark has decreased by 80%, and the council declares the curfew a success. Explain why this conclusion may not be valid.

In order to determine if students on a college campus are in favor of a tuition hike to pay for expanded parking services, a member of the student senate surveys 25 people in a commuter parking lot. Why is this a poor sampling technique?

How does a randomized comparative experiment control the effects of confounding variables?

A marketing company conducted a survey of college students to obtain data for an advertising campaign. They selected 1421 students randomly from campus directories of 132 colleges and universities. The 1421 students represent:

A 10-year study of low-birth-weight babies is performed to determine if birth weight affects IQ and performance in elementary school. Children are identified in hospitals at birth and their performance is tracked until they are 10 years old. This type of study is a(n):

Describe what is meant by the placebo effect in an experiment.

When you estimate a population proportion by sample, which of the following will make the confidence interval narrower?

A group of 100 students is randomly chosen and divided into two groups. One group is taught typing using a set of new materials and the other using traditional methods. After instruction, typing speeds are compared to determine if the new materials improve learning. This type of study is a(n):

What is the difference between an observational study and an experiment?

What is nonresponse?

Use the random digits table above, starting at line 103, to choose five people from a list numbered 01 to 99 to receive a survey.

If an experiment is designed in a way that both of the experimental subjects and the person who interact with them don't know which treatment each subject received, then the experiment is:

Use the following portion of a table of random digits, starting at line 136, to choose four people from a list numbered 20 through 99.

Use the random digits table above, starting at line 102, to choose five people from a list numbered 001 to 500 to receive a survey.

A flashlight manufacturer sets aside a production line for the assembly of 2000 flashlights to fill a special order. Ninety of these flashlights are selected at random from the production line to be tested, and 15 are found to be defective. The population is:

What does it mean to say that the results of an experiment are statistically significant?