In-Class Quiz Questions (Exam #3 Material)

Question 1

If control group participants accidentally found out the purpose of a study, what might be affected?

a) Research bias
b) Reproducibility of the study
c) Validity of the study
d) Reliability of the study

Answer 1

C) VALIDITY OF THE STUDY

Question 2

A study with high intra-rater reliability is one in which:

a) results due to chance.
b) examiner did not score subjects the same way
c) one examiner was consistent in scoring
d) examiner inconsistencies were eliminated

Answer 2

C) ONE EXAMINER WAS CONSISTENT IN SCORING.

Question 3

A study was done 2 years after the first one using the same exact research design and had the exact opposite results. The results from this study can be considered:

a) unreliable
b) reliable
c) invalid
d) valid

Answer 3

A) UNRELIABLE.

Question 4

The term “mode” refers to:

a) the difference between the highest and lowest scores in a series of scores.
b) the exact center of a series of scores.
c) the sum of all the scores.
d) the most frequently appearing score.
e) the average of the sum of all the scores.

Answer 4

D) THE MOST FREQUENTLY APPEARING SCORE.

Question 5

Which of the following is an adequate null hypothesis?

a) Salt water has no effect on plaque.
b) Salt water has an effect on plaque.
c) There is a negative relationship between salt water & plaque.
d) None of the above.

Answer 5

A) SALT WATER HAS NO EFFECT ON PLAQUE.

Question 6

How many modes are there in the following set of gingival index scores?

1.2, 1.5, 1.5, 1.6, 2.0, 2.0, 2.3, 2.4, 2.4, 2.8, 3.0, 3.0

a) 1
b) 2
c) 3
d) 4

Answer 6

D) 4

Question 7

The independent variable represents the:

a) treatment given to an experimental group.
b) placebo given to the control group.
c) outcome of the study.
d) results obtained within the control group.

Answer 7

A) TREATMENT GIVEN TO AN EXPERIMENTAL GROUP.

Question 8

A study conducted to determine which toothpaste (Brand X & Y) was more effective in reducing decay. Which is the independent variable in the study?

a) Number of caries
b) Brand X
c) Brand Y
d) Brand X & Y

Answer 8

D) BRAND X & Y

Question 9

Which statistical test is used to compare plaque score averages (mean) between two classes of 5th graders?

a) ANCOVA (analysis of co-variance)
b) ANOVA (analysis of variance)
c) Chi-square test
d) Student t-test
e) Measures of central tendency

Answer 9

D) STUDENT t-TEST

Question 10

If two variable have perfect negative correlation, correlation coefficient would be:

a) 0
b) 1.0
c) -1.0
d) -0.10

Answer 10

C) -1.0

Question 11

Which of the following correlation coefficients has the strongest relationship?

a) 0
b) -0.87
c) +0.59
d) -0.75
e) +0.80

Answer 11

B) -0.87

[0 or # closest to 0 = no relationship, weakest]

Question 12

Which level of significance represents the maximum allowable “margin of error” in order to validate a study?

a) p = 0.05
b) p = 0.01
c) p = 0.001
d) p = 0.005

Answer 12

A) 0.05

Question 13

In a negatively skewed distribution:

a) there will be more high scores than low scores.
b) there will be more low scores than high scores.
c) all scores will be equally distributed in a lower range.

Answer 13

A) THERE WILL BE MORE HIGH SCORES THAN LOW SCORES.

Question 14

At a significance level of p = 0.50, a correlation coefficient of 0.42 suggests which of the following:

a) no statistical significance & no clinical significance
b) statistical significance & no clinical significance
c) statistical significance & clinical significance
d) no statistical significance & clinical significance

Answer 14

A) NO STATISTICAL SIGNIFICANCE & NO CLINICAL SIGNIFICANCE

Question 15

A study was conducted to determine if a new toothbrush would remove more biofilm on 25 patients. A mean base-line = 5.1 on 6.0 scale. After using the new brush for 2 weeks, mean score for 25 patients was 4.9 where p

Answer 15

D) POST SCORES ARE STATISTICALLY SIGNIFICANT BUT NOT CLINICALLY SIGNIFICANT.