Psych Stats 2

A negative z-score corresponds to a score that is

D. lower than the mean in a distribution

If an entire population with μ= 50 and sd = 4 is transformed into z-scores, then the distribution of z-scores will have a mean ____ and sd of _____

A. μ = 0; sd= 1

What is one reason to calculate a z-score?

B. It allows comparisons with scores from other distributions

Which position in a distribution corresponds to a z-score = -2.00?

B. below the mean by 2 sd

Z-scores are useful because they provide a way to determine if ____

B. a distribution of scores is standarized

Which of the following is the best definition of sampling with replacement?

B. It requires returning each individual to the population before making another selection

Which of the following is a requirement for a random sample?

D. All of the above (equal chance of being selected, probabilities can’t change during selection, the middle 50%)

A vertical line drawn through a norma distribution z= -0.60 separates the distribution in two sections, the body and tail. What proportion of the distribution is the body?

D. 0.73

A class consists of 10 male and 30 female students. A random sample of n=4 students is selected with replacement. If the first three students are all females, what is the probability that the fourth student is male?

B. p= 10/40

What proportion of a normal distribution is located in the tail above z=+1.65

A. 0.05

What of the following is the best definition of sampling error?

B. average difference between the sample and population mean

Which is the standard error of M?

D. the standard deviation of the distribution of sample means

Which of the following is the best definition of the Law of Large Numbers?

B. The larger the sample size, the more likely to sample mean will resemble the population mean.

Which statement below is not consistent with the distribution of sample means?

A. The distribution of sample means tends to pile up around the population sd

Which of the following would cause the standard errorof the M to get smaller?

A. Increasing both the sample size and sd

Which of the followingn is an example of Type I error?

B. A test says you have the flu, but you really don’t

Which of the following accurately describes a hypothesis test?

C. a technique that usws the data from a sample to evaluate a hypothesis about a population

If a hypothesis test produces a z-score in the critical region, which decision should be made?

C. reject the null hypothesis

Which statement below is consistent with making a Type II error?

A. concluding that a treatment has no effect when it really does

Which of the following best describes the critical region?

A. sample means that are very unlikely to be obtained if the null hypothesis is true

WHich of the following is a fundamental difference between t statistics and z scores?

B. The t statistic uses the sample sd in place of the population sd.

In which of the following situations would you be most likely to use a one-sample t-test?

D. A police officer compares the number of tickets he writes in a month to the national average

If two samples are selected from the same population, under which circumstances will the two samples have exactly the same t statistic?

D. The samplesn are the same size, have the same mean, and have the same variance

Which set of characteristics will produce the smallest value for the estimated sd?

A. a large sample size and a small sample sd