Deck 5: Statistical Inference

Question 1

Probabilities are traditionally shown as values ranging from ____ to ____.

A) -1.00, +1.00
B) .00, 1.00
C) 0.0, 100.0
D) -100.0, +100.0

Answer 1

B

Question 2

On a 36-slot roulette wheel (that is, excluding values for "0" or "00"), what is the probability of a roulette spin yielding an even number?

A) .028
B) .25
C) .50
D) 1.00

Answer 2

C

Question 3

What does the symbol H₀ represent?

A) A directional hypothesis
B) A nondirectional hypothesis
C) A research hypothesis
D) A null hypothesis

Answer 3

D

Question 4

Descriptive statistics are rarely exactly equal to population parameters because of:

A) Sampling error
B) Attrition bias
C) Type I errors
D) Type II errors

Question 5

A sampling distribution of the mean is a distribution of:

A) Population values from an entire population
B) Sample values from a random sample
C) Sample means from an infinite number of samples of a given size
D) Sample values from a sample of samples of a given size

Question 6

In a sampling distribution of the mean, which of the following is true?

A) The mean is equal to 0.0.
B) The mean is equal to the population mean.
C) The distribution is a t distribution.
D) The distribution is a binomial distribution.

Question 7

The statistic referred to as the SEM is:

A) The standard deviation of population values
B) The standard deviation of a sampling distribution of means
C) The standard error of measurement
D) The standard estimate of the mean

Question 8

The formula for estimating the SEM involves which two components?

A) The mean and SD from a sample
B) The mean and SD from the population
C) The SD from a sample and number of cases in the population
D) The SD from a sample and number of cases from that sample

Question 9

Given a mean of 50.0 and an SD of 10.0, which of the following would have the smallest estimated SEM?

A) A sample size of 50
B) A sample size of 250
C) A sample size of 500
D) It cannot be determined without knowing the size of the population.

Question 10

Because of an interest in precision, researchers prefer:

A) Small SEMs
B) Large SEMs
C) A true SEM rather than an estimated SEM
D) An SEM based on population rather then sample values

Question 11

Which of the following statements is true?

A) Parameter estimation is more frequently used by nurse researchers than hypothesis testing.
B) Point estimation is preferred to interval estimation.
C) Interval estimation involves constructing a confidence interval around a point estimate of a parameter.
D) Estimation procedures are appropriate for estimating population means but not percentages.

Question 12

Which of the following would be an element in the formula for computing confidence limits around a sample mean?

A) The 95% CI
B) A value from the t distribution for a specified sample size
C) The value of 1.96, corresponding to z
D) The sample SD

Question 13

In the expression, M = 10.0, 95% CI = 8.0, 12.0, which of the following is true?

A) There is a 5% probability that the population mean is greater than 12.0.
B) There is a 2 ½% probability that the population mean is greater than 12.0.
C) 95% of all population means are between 8.0 and 12.0.
D) The population mean has a 95% probability of being 10.0.

Question 14

The appropriate theoretical distribution for constructing confidence intervals around an odds ratio is:

A) A sampling distribution of the mean
B) A normal distribution
C) A t distribution
D) A binomial distribution

Question 15

Which of the following is true regarding a 95% CI around a proportion?

A) If the actual proportion is .00, the lower limit of the CI is a negative value.
B) The theoretical distribution is more skewed when the proportion is .50 than when it is.10
C) The closer the proportion is to .50, the wider the CI.
D) The larger the sample size, the wider the CI.

Question 16

In hypothesis testing, which of the following is true?

A) The null hypothesis is assumed to be true.
B) Researchers seek to reject the null hypothesis with 100% certainty.
C) p = 1.0 that a true null will be rejected or that a false null will be accepted.
D) The null hypothesis is the same as the research hypothesis.

Question 17

A Type I error:

A) Is the inverse of power
B) Means that the researcher has come to a false-negative conclusion
C) Only occurs when the test is two tailed
D) Has a risk of occurrence that is under the researchers' control by designating α

Question 18

The level of significance (significance criterion) of a statistical test:

A) Is the power of the test to reject the null when it is false
B) Is a probability level, typically .05
C) Is a probability level, typically .95
D) Is automatically computed when tests are performed by computer

Question 19

The probability of committing a Type II error:

A) Is greater when α is .01 than when α is .05
B) Is always greater than the probability of committing a Type I error
C) Is equivalent to 1 - α
D) Is under the control of researchers by establishing a level for β

Question 20

In a one-sample ?t-test:

A) A sample mean for one group is tested against a sample mean for another group
B) A sample mean is tested against the value of 50.0
C) A sample mean is tested against a hypothesized value for the population mean
D) A sample mean is tested against the population parameter

Question 21

When a result is statistically significant, this means that:

A) The result has a low probability of being due to chance factors
B) The result is true
C) The result is clinically important
D) The result will be replicated in other similar studies

Question 22

In a one-sample ?t-test, if the obtained t = -3.21 and the tabled t = 2.01 for α = .05, this means:

A) The null hypothesis is wrong
B) The null hypothesis is right
C) The null hypothesis can be accepted
D) The null hypothesis can be rejected

Question 23

Which of the following two terms belong together?

A) Null hypothesis, one-tailed test
B) Directional hypothesis, one-tailed test
C) Null hypothesis, two-tailed test
D) Directional hypothesis, two-tailed test

Question 24

Which of the following is an assumption of a parametric test?

A) The central limit theorem is applicable.
B) The population values follow a t distribution.
C) The sample was randomly selected from the population.
D) The risk of a Type I error is .05.

Question 25

Nonparametric tests are more likely to be appropriate than parametric tests when:

A) The dependent variable is severely skewed
B) The dependent variable is measured on at least an interval scale
C) The sample size is large
D) Values in the population are normally distributed

Question 26

A within-subjects test would be required in a study in which:

A) Outcomes for a group are compared before and after an intervention
B) Men are compared to women
C) Lung cancer patients are compared to colon cancer patients
D) Older participants are compared to younger ones

Question 27

In a one-sample t-test for a study involving 200 study participants, df would equal:

A) .05
B) 1
C) 199
D) 200 % t

Question 28

If a statistical test yields a p = .004, this means that:

A) The probability is 4 in 100 that the research hypothesis is true
B) The probability is 4 in 1,000 that the research hypothesis is true
C) The probability is 4 in 100 that the null hypothesis is true
D) The probability is 4 in 1,000 that the null hypothesis is true

Question 29

^aLate extubation = More than 5 hours of mechanical ventilation
-Refer to Table 5. Which of the following numbers is a point estimate for a risk index for delayed extubation?

A) 19.2
B) 29.8
C) 1.66
D) 1.14

Question 30

^aLate extubation = More than 5 hours of mechanical ventilation
-Refer to Table 5. Which patient characteristic was most associated with a higher risk of delayed extubation?

A) Sex
B) Race
C) Hypertensive status
D) Prior experience with CABG

Question 31

^aLate extubation = More than 5 hours of mechanical ventilation
-Refer to Table 5. What is the probability that the OR for delayed extubation for women is less than 1.14?

A) .025
B) .05
C) .50
D) .95

Question 32

^aLate extubation = More than 5 hours of mechanical ventilation
-Refer to Table 5. Which patient characteristic was not associated with a significantly higher risk of delayed extubation?

A) Sex
B) Race
C) Hypertensive status
D) Prior experience with CABG