Basic statistics Quiz 1: ch.1

Lawrence is testing a series of new commercials on a sample audience for an advertising company. He wants to see which of 10 commercials receives the highest rating from audiences and he wants to use a different audience for each commercial. What design should Lawrence use?

between-groups

Maria wants to know if identical twins raised in different environments have different IQ scores. What type of research design is not available for Maria to use because she cannot randomly assign the participants?

experimental

Matthew is interested in measuring whether there is a difference in time spent sleeping at night in a given week between elementary school-aged children and high school-aged students. In this study, the independent variable is most likely to be:

age

Random assignment refers to a situation in which:

every participant in the study has an equal chance of being assigned to any condition or level of the independent variable

The Consideration of Future Consequences scale is intended to measure the extent to which an individual considers the future when making immediate choices. If the scale were a reliable measure, we would expect that:

a person's score on the scale would be relatively stable from day to day

________ variables are those that can take on only certain numbers such as whole numbers.

Discrete

The CDC is testing the effectiveness of a recent campaign promoting a healthy lifestyle. What is the best operational definition for "healthy lifestyle"?

Each day eat 5 servings of fruit/vegetables and be physically active for 30 minutes or more

A popular sports drink company sampled 20 people who drink its product regularly and found that they performed better during a physical test than did those who do not drink the product regularly. What might be a possible confound in the study?

People who are regular drinkers of sports drinks may be more athletic than those who are not

Dr. Feldman was interested in the effect of Valium on motor performance. He injected 30 rats in the experimental group with a small amount of Valium and 30 rats in the control group with saline solution. Following injection, he measured the rate of bar pressing by both groups of rats. On average, rats in the control group had 800 presses per hour and rats in the experimental group had 715 presses per hour. The same testing box was used for both groups of rats, but different student assistants tested the control and experimental groups. In this example, having two different student assistants test the two groups is a(n) ________ variable.

confounding

One reason for doing correlational research is to evaluate the relationship between two variables that are related to each other either positively or negatively. However, a correlation is vulnerable to what type of variable, which systematically co-varies with the variable of interest?

confounding

A variable for which there is an infinite number of values between any two points on the scale is a ________ variable.

continuous

The amount of food a person eats each week (as measured in ounces) would be a ________ variable.

continuous and ratio

Which "branch" of statistics uses numerical observations and incorporates them into an organized and informative summary of the data?

descriptive

The U.S. Census records the number of people in each household. What type of data are these?

discrete

A researcher was interested in assessing whether a new medication had negative side affects on reaction time. He performed an experiment on a group of rats. One group of rats received the medication, and the other group of rats did not. The researcher then measured reaction time differences between the two groups on a series of tasks. In this experiment, the independent variable is:

medication.

In an experiment designed to assess the effects of disclosure of ingredients on the experience of taste, Lee, Frederick, and Ariely (2006) approached patrons at a local pub and asked them to taste and rate a new beer, the MIT Brew, on a taste rating scale. Some participants were told about the secret ingredient in the beer (a few drops of balsamic vinegar) either before tasting (before condition) or after tasting but before rating (after condition). Other participants were not told anything regarding the secret ingredient (not told condition). Which of the following aspects of this study is an operational definition of the dependent variable?

participants' responses on the taste rating scale

Which of the following types of variables are considered scale variables by statistical computing packages such as SPSS?

ratio and interval

A researcher was interested in assessing whether a new medication had negative side affects on reaction time. He performed an experiment on a group of rats. One group of rats received the medication, and the other group of rats did not. He then measured reaction time differences between the two groups on a series of tasks. In this experiment, the dependent variable is:

reaction time.

College students at 20 campuses around the country were polled to find out how many students own MP3 players. This small representative group of students is called

sample.

A New York Times article published on April 24, 2007, reported the research of Dr. Vallortigara, a neuroscientist at the University of Trieste, Italy. In this study, Dr. Vallortigara assessed whether a dog's tail wags in a preferred direction in response to positive as opposed to negative stimuli. First Dr. Vallortigara recruited 30 dogs that were family pets. While filming a dog's tail from above he allowed the dog to view (through a slot in its cage) its owner, an unfamiliar human, a cat, and an unfamiliar, dominant dog. The study found that dogs' tails wagged to the right for the owner and to the left for the unfamiliar, dominant dog. What is the dependent variable in this study?

tail wagging, either to the right or left

A researcher wanted to determine whether eating Pop-Tarts for breakfast increase the aggression of second graders during their morning play period. After feeding a group of 20 students Pop-Tarts for breakfast she observed that, on average, the students committed 4.5 aggressive behaviors during their morning play period. In this example, the sample is:

the 20 students the researcher observed.

A researcher wanted to determine whether eating Pop-Tarts for breakfast increased the aggression of second graders during their morning play period. After feeding a group of 20 students Pop-Tarts for breakfast she observed that, on average, the students committed 4.5 aggressive behaviors during their morning play period. In this example, the descriptive statistic is:

the 4.5 aggressive behaviors

Jonathon has taken the GRE three times. Every time he takes it he gets a 500 on the math section. This implies that:

the GRE is a reliable test

Matthew is interested in measuring whether there is a difference in time spent sleeping at night in a given week between elementary school-aged children and high school-aged students. In this study, the dependent variable is most likely to be:

time spent sleeping

When a test measures what it is intended to measure, the test is said to be

valid