Which is NOT true of an experimental or prospective research design?
A. Dependent variables affect independent variables.
B. Cause and effect relationships can be inferred.
C. The experiment can be planned before the effect has occurred.
D. It is the ideal research design.
Which of the following correctly characterizes the difference between a parallel clinical trial and a crossover trial?
A. Only the parallel design has a washout period.
B. All participants have the advantage of the experimental treatment in the crossover design.
C. The crossover design only has one experimental phase.
D. The parallel design does not have a control group.
Which of the following correctly characterizes the difference between cross-sectional and longitudinal designs?
A. It is easier to show a cause and effect relationship with the longitudinal design.
B. The cross-sectional design assesses the same individuals at different time points.
C. It is quicker to do the longitudinal design.
D. The longitudinal design assesses a sample of individuals at one time.
Which of the following is a method for minimizing bias?
A. Nonrandom assignment of subjects to treatment groups.
B. Have the subjects know to which group they have been assigned.
C. Have the investigators know which individuals will be in each group.
D. Place controls on as many influencing factors as possible up front.
Identification of cause and effect relationships is best facilitated by _______________.
A. a prospective research design
B. a retrospective research design
C. allowing extraneous variables to influence results
D. allowing the Hawthorne effect to influence results
A. A method for assigning subjects to treatment groups.
B. A method for determining the reliability of scoring.
C. A method for determining sample size.
D. A statistical test for determining differences between treatments.
Which of the following methods is NOT appropriate for generating random numbers?
A. Drawing names from a hat.
B. Picking every 7th name from a list.
C. Random number software program.
D. Random number table.
Which of the following is NOT appropriate in determining the size of the sample for an investigation?
A. Large enough to accommodate the expected loss of subjects during the investigation.
B. Large enough to demonstrate the differences between groups by statistical logic.
C. Make the sample very large so trivial differences reach statistical significance.
D. Minimal size of the group should be 26 to 30 subjects.
The measures of central tendency include which of the following?
D. All of the above.
The collection of individuals that falls between one standard deviation below and one above the mean comprises approximately _____ of a normally distributed population.
When the p-value is set at 0.05 in an experiment comparing two different therapies, this typically means that there is _______________.
A. no more than a 5% risk that a statistical finding of a "difference" is due to chance
B. no more than a 0.05% risk that a statistical finding of a "difference" is due to chance
C. a greater than 50% risk that a statistical finding of a "difference" is due to chance
D. a greater than 95% risk that a statistical finding of a "difference" is due to chance
In an experiment comparing the efficacy of two different therapies where a t-test demonstrates a p value of 0.001, this means _______________.
A. no significant difference was found
B. a significant difference was found
C. the two therapies were equivalent
D. there is a 0.1% risk that the difference is real
Which of the following information should be included for each inferential statistical test?
A. p value
B. If p value is statistically significant.
C. Value of the test statistic.
D. All of the above.
Which of the following is a scientific basis for the recommendation of new therapy?
A. The belief by the investigator that a new therapy is better.
B. A volume of scientific reports supports the new therapy or product.
C. The cost is greater than the benefit.
D. Results are statistically significant but not clinically important.
Why do examiners, scoring oral disease levels in an experiment, need to be calibrated?
A. So that all the examiners use the same criteria for scoring.
B. So that the measurement of disease has a reliability level as close to “1” as possible.
C. So that the results are an accurate measure of the disease level of the sample.
D. All of the above.