Question 1

If your probability of a Type Il error is .30,then your statistical power is:
A).30
B).05
C).70
D).80

Accepted Answer

The statistical power is the probability of correctly rejecting a false null hypothesis. It is equal to 1 minus the probability of a Type II error.

Probability of Type II error = 0.30 
Therefore, 
Statistical power = 1 - 0.30
Statistical power = 0.70

Hence, the correct answer is C) .70.

Question 2

An a priori statistical power analysis can be used to determine how large a sample to select.

Accepted Answer

An a priori power analysis is specifically used to determine the sample size needed to achieve a certain level of statistical power.

Question 3

Ignoring statistical power can result in
A) conducting a study with a sample size that is too small.
B) wasting resources by selecting a sample that is much smaller than needed.
C) overlooking the probability of committing a Type I error.
D) nonparametric outcomes.

Accepted Answer

Ignoring statistical power can lead to conducting a study with a sample size that is too small, which may not detect a true effect if it exists.

Question 4

The probability of a Type II error increases when
A) lower significance levels are used.
B) larger sample sizes are selected.
C) a stronger relationship in the population is assumed.
D) statistical power is calculated on a post hoc bsis.

Accepted Answer

Lower significance levels mean that the researcher is less willing to accept evidence against the null hypothesis, which increases the chances of failing to reject the null hypothesis when it is actually false, leading to a Type II error.

Question 5

The t-test is appropriate to use when testing the significance of the relationship between two nominal level variables.

Accepted Answer

The t-test is appropriate to use when testing the significance of the relationship between two continuous level variables, not nominal level variables. The appropriate test for nominal level variables is the chi-square test.

Question 6

Which statistical significance test should be used in a study of whether the mean number of days worked by case-managed clients is greater than the mean worked by non-case-managed clients?
A) t-test.
B) chi-square.
C) Pearson's product-moment r.
D) Fisher's exact test.

Accepted Answer

A t-test is appropriate for comparing the means of two independent groups, which is what is being asked in this study. Chi-square is used for categorical data, Pearson's product-moment r is used for correlation analysis, and Fisher's exact test is used for small sample sizes in contingency tables.

Question 7

Parametric tests assume
A) interval- or ratio-level measurement of all variables.
B) a normal sampling distribution of variables with interval- or ratio-level data.
C) nonprobability sampling.
D) nominal level measurement of all variables.

Accepted Answer

Parametric tests assume a normal sampling distribution of variables with interval- or ratio-level data.

Question 8

A statistical power analysis tells us:
A)How large our effect size is.
B) The probability of avoiding a Type II error assuming our hypothesis is true.
C) The probability of committing a Type I error.
D) How much substantive significance our findings have.

Accepted Answer

A statistical power analysis calculates the probability of avoiding a Type II error (false negative) assuming our hypothesis is true. It helps us determine the sample size needed to detect a certain effect size with a certain level of confidence.

Question 9

Which of the following statistics can be used to determine whether or not there is a statistically significant relationship between two nominal-level variables?
A) Gamma
B) Chi-square
C) Analysis of variance
D) Pearson's product-moment correlation coefficient

Accepted Answer

Chi-square is the appropriate statistical test for determining whether or not there is a statistically significant relationship between two nominal-level variables. Gamma is a measure of association for ordinal-level variables, analysis of variance is for comparing means of continuous variables, and Pearson's correlation coefficient is for measuring the linear relationship between two continuous variables.

Question 10

Which of the following statistics can be used to determine whether there is a statistically significant difference between three treatment groups in number of days hospitalized?
A) t-test
B) chi-square
C) analysis of variance
D) Pearson's product-moment r

Accepted Answer

Analysis of variance (ANOVA) can be used to compare means between three or more groups. The t-test is only used to compare means between two groups, while chi-square is used for comparing categorical data. Pearson's product-moment r is used for measuring the strength of a correlation between two continuous variables.

Question 11

Which of the following statements is/are true about a multivariate statistical analyses in which variable A has a .20 correlation with variable C,and variable B has a .20 correlation with variable C?
A)Variables A and B together must accounor 40 percent of the variation in variable C.
B) Variables A and B together must accounor 4 percent of the variation in variable C.
C) If variables A and B are correlated with each other, then variables A and B together will accounor less than 40 percent of the variation in variable C.
D) If variables A and B are correlated with each other, then variables A and B together will accounor more than 40 percent of the variation in variable C.

Accepted Answer

If variables A and B are correlated with each other, the shared variance between them means they will account for less than the sum of their individual contributions to the variation in variable C.

Question 12

Nonparametric tests are intended for use when some assumptions of parametric tests cannot be met.

Accepted Answer

Nonparametric tests do not require the same assumptions that parametric tests do, such as normal distribution of the data or equal variances. Therefore, they can be used when these assumptions cannot be met.

Question 13

A rigorous and trustworthy meta-analysis worthy of guiding evidence-based practice decisions should:
A) include published studies, only.
B) be transparent about potential conflicts of interest.
C) calculate one mean effect size based on all included studies, regardless of their methodological strengths or weaknesses.
D) avoid calculating the overall level of statistical significance.

Accepted Answer

Transparency about potential conflicts of interest is important for ensuring the credibility and trustworthiness of a meta-analysis. This helps readers to interpret the results and make informed decisions based on the evidence provided.

Question 14

If two correlated variables each have a bivariate correlation of .25 with a third variable,then the multiple correlation of the three variables combined will be .50.

Accepted Answer

Correlation between two variables does not directly indicate the multiple correlation between all three variables. The true multiple correlation would depend on the strength and direction of the correlation between the two variables, as well as the unique variance each variable contributes to the third variable. It is possible for the multiple correlation to be greater or less than .50 in this scenario.

Question 15

A researcher conducts 20 tests of statistical significance,one for each independent variable,wita.05 significance level.Only one test yields a probability value that is not greater than .05.What can we infer about the latter test?
A) The probability of committing a Type I error in rejecting the null hypothesis is .05.
B) It is a statistically significant predictor of the dependent variable.
C) Because so many tests were conducted, the probability of committing a Type I error is greater than .05.
D) Because so many tests were conducted, the probability of committing a Type I error is much smaller than .001.

Accepted Answer

The answer of A researcher conducts 20 tests of statistical...

Question 16

Multiple regression analysis shows the overall correlation between each of a set of independent variables and an interval- or ratio-level dependent variable.

Accepted Answer

Multiple regression analysis is used to identify the overall correlation between multiple independent variables and one dependent variable, which is typically interval or ratio-level. Therefore, the statement is true.

Question 17

Chi-square should be used to test the significance of relationships between the ratio level variables.

Accepted Answer

Chi-square should be used to test the significance of relationships between categorical variables, whereas correlation tests should be used to test the significance of relationships between ratio level variables.

Question 18

Statistical power increases when
A) larger sample sizes are selected.
B) lower significance levels are used.
C) a weaker relationship in the population is assumed.
D) it is done on a post hoc basis.

Accepted Answer

Statistical power increases when larger sample sizes are selected. This is because a larger sample size can increase the likelihood of detecting a true effect, even if it is small.

Question 19

An experiment is conducted to test the effectiveness of a social work intervention.The experimental group improves more than does the control group,but the results are not statistically significant.This means that
A) the intervention was not effective.
B) the intervention was effective, but not at a significant level.
C) we cannot rule out sampling error in inferring about the effectiveness of the intervention.
D) the sample size was too large.

Accepted Answer

The fact that the experimental group improved more than the control group indicates that the intervention may have been effective, but the lack of statistical significance means that we cannot rule out the possibility that the difference between the two groups is due to chance or sampling error. Therefore, we cannot confidently conclude that the intervention was effective.

Question 20

If your statistical power is .60,then your probability of a Type II error is .40.

Accepted Answer

Statistical power is the probability of correctly rejecting a false null hypothesis, which is 1 minus the probability of a Type II error (β). Therefore, if power is 0.60, β is 0.40.

Quiz 23: Inferential Data Analysis

If your probability of a Type Il error is .30,then your statistical power is:

An a priori statistical power analysis can be used to determine how large a sample to select.

Ignoring statistical power can result in

The probability of a Type II error increases when

The t-test is appropriate to use when testing the significance of the relationship between two nominal level variables.

Which statistical significance test should be used in a study of whether the mean number of days worked by case-managed clients is greater than the mean worked by non-case-managed clients?

Parametric tests assume

A statistical power analysis tells us:

Which of the following statistics can be used to determine whether or not there is a statistically significant relationship between two nominal-level variables?

Which of the following statistics can be used to determine whether there is a statistically significant difference between three treatment groups in number of days hospitalized?

Which of the following statements is/are true about a multivariate statistical analyses in which variable A has a .20 correlation with variable C,and variable B has a .20 correlation with variable C?

Nonparametric tests are intended for use when some assumptions of parametric tests cannot be met.

A rigorous and trustworthy meta-analysis worthy of guiding evidence-based practice decisions should:

If two correlated variables each have a bivariate correlation of .25 with a third variable,then the multiple correlation of the three variables combined will be .50.

A researcher conducts 20 tests of statistical significance,one for each independent variable,wita.05 significance level.Only one test yields a probability value that is not greater than .05.What can we infer about the latter test?

Multiple regression analysis shows the overall correlation between each of a set of independent variables and an interval- or ratio-level dependent variable.

Chi-square should be used to test the significance of relationships between the ratio level variables.

Statistical power increases when

An experiment is conducted to test the effectiveness of a social work intervention.The experimental group improves more than does the control group,but the results are not statistically significant.This means that

If your statistical power is .60,then your probability of a Type II error is .40.