PubH 6002
QUIZ 5 Answer Key
Biostatistical Applications for Public Health
George Washington University
This Document Description:
Complete PubH 6002: Biostatistical
Applications for Public Health Quiz 5 Answer
Key (MCQs with fully worked solutions)
, PubH 6002: Biostatistical Applications for Public Health
Quiz 5 - Key
Student Name: _________________________
Instructions: This quiz consists of 24 MC questions. While this quiz is designed to take 35
minutes, you have 2 hours to complete it. Work individually! You may use your own formula
sheets containing relevant hand-written notes as well as a standard or scientific calculator. To
receive full credit, you must show all of your work. Good luck!
Quade (1992) 1 reports data obtained by Cartwrigtht, Lindahl and Bawden (1968) 2 in their two-
year study designed to evaluate the effectiveness of two treatments in reducing the incidence of
dental caries, as compared with a placebo. The two treatments were stannous fluoride (SF) and
acid-phosphate fluoride (APF), and the placebo was distilled water (W). A total of 69 female
children completed the study. For each child, the number of decayed, missing or filled teeth
(DMFT) was recorded before (B) and after (A) the study; the response to be analyzed is the
difference (or change) in the number of DMFT, calculated as Y = A – B. Covariates that could
be taken into account are (1) the initial DMFT count (before), (2) the age (in years) at the
beginning of the study, and (3) the institution where the child resided (there were 3 different
institutions). Using a 0.05 significance level and the given computer output, you need to test the
claim that the children in the three treatment groups have a different mean change in the number
of DMFT by answering the questions that follow. Note that the change in the number of DMFT,
the initial DMFT count and age can be considered continuous here, whereas the institution and
treatment group are categorical.
For questions 1-5, examine the computer output of the five different models provided for you in
the separate packet labeled SAS Output #1-SAS Output #5. Match the output with the most
appropriate analysis. You may select each letter (method) more than once, once or not at all.
(1 point each)
1. SAS Output #1 c a. ANCOVA
2. SAS Output #2 e b. Multiple linear regression
3. SAS Output #3 d c. One-way ANOVA
4. SAS Output #4 a d. Two-way ANOVA with an interaction
5. SAS Output #5 b e. Two-way ANOVA without an interaction
1
Quade D. (1982). Nonparametric Analysis of Covariance by Matching. Biometrics 28, 597-611.
2
Cartwright HV, Lindahl RL, Bawden JW. (1968). Clinical findings on the effectiveness of stannous fluoride and
acid phosphate fluoride as caries reducing agents in children. Journal of Dentistry for Children 35, 36-40.
QUIZ 5 Answer Key
Biostatistical Applications for Public Health
George Washington University
This Document Description:
Complete PubH 6002: Biostatistical
Applications for Public Health Quiz 5 Answer
Key (MCQs with fully worked solutions)
, PubH 6002: Biostatistical Applications for Public Health
Quiz 5 - Key
Student Name: _________________________
Instructions: This quiz consists of 24 MC questions. While this quiz is designed to take 35
minutes, you have 2 hours to complete it. Work individually! You may use your own formula
sheets containing relevant hand-written notes as well as a standard or scientific calculator. To
receive full credit, you must show all of your work. Good luck!
Quade (1992) 1 reports data obtained by Cartwrigtht, Lindahl and Bawden (1968) 2 in their two-
year study designed to evaluate the effectiveness of two treatments in reducing the incidence of
dental caries, as compared with a placebo. The two treatments were stannous fluoride (SF) and
acid-phosphate fluoride (APF), and the placebo was distilled water (W). A total of 69 female
children completed the study. For each child, the number of decayed, missing or filled teeth
(DMFT) was recorded before (B) and after (A) the study; the response to be analyzed is the
difference (or change) in the number of DMFT, calculated as Y = A – B. Covariates that could
be taken into account are (1) the initial DMFT count (before), (2) the age (in years) at the
beginning of the study, and (3) the institution where the child resided (there were 3 different
institutions). Using a 0.05 significance level and the given computer output, you need to test the
claim that the children in the three treatment groups have a different mean change in the number
of DMFT by answering the questions that follow. Note that the change in the number of DMFT,
the initial DMFT count and age can be considered continuous here, whereas the institution and
treatment group are categorical.
For questions 1-5, examine the computer output of the five different models provided for you in
the separate packet labeled SAS Output #1-SAS Output #5. Match the output with the most
appropriate analysis. You may select each letter (method) more than once, once or not at all.
(1 point each)
1. SAS Output #1 c a. ANCOVA
2. SAS Output #2 e b. Multiple linear regression
3. SAS Output #3 d c. One-way ANOVA
4. SAS Output #4 a d. Two-way ANOVA with an interaction
5. SAS Output #5 b e. Two-way ANOVA without an interaction
1
Quade D. (1982). Nonparametric Analysis of Covariance by Matching. Biometrics 28, 597-611.
2
Cartwright HV, Lindahl RL, Bawden JW. (1968). Clinical findings on the effectiveness of stannous fluoride and
acid phosphate fluoride as caries reducing agents in children. Journal of Dentistry for Children 35, 36-40.
