08 Oct An experiment was conducted as a one-way factorial design with K sample means, each based on n scores. What is the number of degrees of freedom for the between mean squares?

Epidemiology and Biostatistics for Public Health Application 2

An experiment was conducted as a one-way factorial design with K sample means, each based on n scores. What is the number of degrees of freedom for the between mean squares?

 

n – 1

 

K – 1

 

n – K

 

 (n – 1)(K – 1)

 

Question 2A screening examination was performed on 250 persons for factor X, which is found in disease Y. A definitive diagnosis for disease Y among the 250 persons had been obtained previously. The results are charted here:

 

30%.

 

70%.

 

56%.

 

7%.

 

80%.

 

Question 3A screening examination was performed on 250 persons for factor X, which is found in disease Y. A definitive diagnosis for disease Y among the 250 persons had been obtained previously. The results are charted here:

 

30%.

 

70%.

 

56%.

 

7%.

 

80%.

 

Question 4A test developed to assess age-related changes in bone density that does not pick up these changes has:

 

low predictive validity.

 

low concurrent validity.

 

low construct validity.

 

None of these is correct.

 

Question 5A test that determines whether disease is actually present is a:

 

screening test.

 

diagnostic test.

 

reliability test.

 

None of these is correct.

 

validity test.

 

Question 6Consider the table below. If all samples sizes are equal then the study used___?

 

Analysis of Variance

 

Source  SS           Df           MS         F

 

Between samples            722.7     4              180.68   15.3

 

Within samples 473.3     40           11.84    

 

Total      1196.0   44                           

 

4 samples of size 10

 

5 samples of size 10

 

4 samples of size 9.

 

5 samples of size 9

 

Question 7Drs. Poke and Jab conducted an employee health program that used five screening tests at the same time to detect several diseases among workers. Which type of program is this?

 

Selective screening

 

Mass screening

 

Ad hoc screening

 

 Multiphasic screening

 

Opportunistic screening

 

Question 8 Figure 11-12 represents different combinations and qualities of validity and reliability (high vs. low). Which set of symbols represents high validity?

 

A set

 

B set

 

C set

 

Both A and C sets

 

None of these is correct.

 

Question 9 Figure 11-12 represents different combinations and qualities of validity and reliability (high vs. low). Which set of symbols represents high reliability?

 

A set

 

B set

 

C set

 

Both A and C sets

 

None of these is correct.

 

Question 10 Figure 11-12 represents different combinations and qualities of validity and reliability (high vs. low). Which set of symbols represents low reliability?

 

A set

 

B set

 

C set

 

Both A and C sets

 

None of these is correct.

 

Question 11 Figure 11-12 represents different combinations and qualities of validity and reliability (high vs. low). Which set of symbols represents high validity but low reliability?

 

A set

 

B set

 

C set

 

Both A and C sets

 

None of these is correct.

 

Question 12If the critical region for a test of hypothesis is F > 9.48773 and the computed value of F from the data is 0.86 then which of the following is correct?

 

The null hypothesis should be rejected.

 

The alternate hypothesis is two-tailed.

 

The significance level is given by the area to the right of 9.48773 under the appropriate F-distribution.

 

The significance level is given by the area to the left of 9.48773 under the appropriate F-distribution.

 

 Question 13In a simple analysis of variance problem, which of the following is an estimate of the variance of individual measurements (after the various effects have been accounted for)?

 

   MS(between)

 

MS(within)

 

MS(total)

 

None of the above

 

Question 14In a study of the influence of yogurt consumption and immunity (Van de Water, Keen, & Gershwin, Journal of Nutrition, 1999) there were three study groups per age group (young adults and senior adults). Live-culture yogurt, pasteurized yogurt and control (no yogurt) were given to each age group in portion sizes of    200 grams per day for 1 year. To which sets of data would you attach dummy variables when coding for a three-group experimental design?

 

The two groups given yogurt

 

The young adult age group

 

The senior adult age group

 

b and c

 

Question 15Lead time bias is best described as:

 

an apparently lower survival rate among persons screened compared to an unscreened group.

 

an actually longer survival time for persons identified during a screening program because they were given an effective treatment.

 

a similar survival time for persons identified during a screening program relative to persons who are diagnosed by clinical symptoms.

 

an apparently longer survival time among persons identified during a screening program because they were identified at an earlier stage of their disease.

 

Question 16Sensitivity and specificity of a screening test refer to its:

 

reliability.

 

validity.

 

yield.

 

repeatability.

 

None of these is correct.

 

Question 17The degree of agreement among several trained experts refers to:

 

internal consistency.

 

repeated measures.

 

concurrent validity.

 

interjudge reliability.

 

both internal consistency and concurrent validity.

 

 Question 18The total variation in response, assuming no bias, is due to error (unexplained variation) plus differences due to treatments (known variation). If known variation is large compared to unknown variation, which of the following conclusions can be drawn?

 

There is no difference in response due to treatments.

 

There is a difference in response due to treatments.

 

The treatments are not comparable.

 

The cause of the response is due to something other than treatments.

 

Review page 394-396 of your textbook for more information on this question.

 

Question 19What does the term ‘familywise error rate’ mean?

 

The probability of a Type II error occurring

 

The error rate across statistical tests conducted on different experimental data

 

The error rate across statistical tests conducted on the same experimental data

 

a and c

 

Question 20What is the definition of ‘mean square’’?

 

A sum of squares divided by its degrees of freedom

 

The square root of the mean

 

The square of the mean

 

A table of means with four cells

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