Review for Unit 6 Exam

Bias in sampling method is

• any error in the sample result, that is, any deviation of the sample result from the truth about the population

• the random error due to using chance to select a sample

• any error due to practical difficulties such as contacting the subjects selected

• Any systematic error that tends to occur in the same direction when you use this sampling method.

• racism or sexism on the part of those who take the sample

You wonder if TV ads are more effective when they are longer or repeated more often or both. So you design an experiment. You prepare 30 second and 60 second ads for a camera. Your subjects all watch the same TV program, but you assign them at random to four groups. One group sees the 30 second ad once during the program; another sees it three times; the third group sees the 60 second add once; and the last group sees the 60 second add three times. You ask all subjects how likely they are to buy the camera.

• This is a randomized block design, but not a matched pairs design.

• This is a matched pairs design.

• This is a completely randomized design with one explanatory variable.

• This is a completely randomized design with two explanatory variables.

• This is a completely randomized design with four explanatory variables.

A recent study examined 699 car accidents in Toronto over a fourteen- month period. Records of phone service providers were used to determine whether the driver was using a cell phone during or immediately before an accident. Overall, the researchers found that the drivers using cell phones were 4.3 times as likely to have an accident than drivers who were not using a cell phones. The result was statistically significant. Which of the following can be concluded from this study.

• Cell phone use increases the likelihood of a car accident.

• There is an association between cell phone use and accidents, but not necessarily a causal relationship.

• There is a correlation between cell phone use and accidents, but not necessarily an association.

• the association between cell phone use and accidents is negative.

• Cell phone use causes more accidents in Canada, but not necessarily in the US.

Suppose you take a random sample of size 25 from a population with mean 120 and standard deviation of 15. Your sample has a mean of 115 and a standard deviation of 13.8. Which of the following has a mean of 120 and a standard deviation of 3?

• the distribution of the population

• the distribution of the sample data

• the sampling distribution of the sample mean

• the sampling distribution of the population mean

• No important distribution related to this situation has the given mean and standard deviation

• A

• B

• C

• D

Which of the following statements is correct about a parameter and a statistic associated with repeated random samples of the same size from the same population?

• Values of the parameter will vary from sample to sample, but values of a statistic will not

• Values of both the parameter and the statistic may vary from sample to sample.

• Values of the parameter will vary according to the sampling distribution for that parameter

• Values of the statistic will vary according to the sampling distribution for that statistic

Five hundred (500) random samples of size n=900 are taken from a large population in which 10% are left-handed. The proportion of the sample that is left-handed is found for each sample and a histogram of these 500 proportions is drawn. Which interval covers the range into which about 68% of the values in the histogram will fall?

• .1 ± .010

• .1 ± .0134

• . .1 ± .0167

• . .1 ± .020