Biostatistics

A
Guide to Design, Analysis and Discovery

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sp; **Self-Test Questions (Chapter 3)**

= 1. Which one of the following graphic tools uses the actual numerical values in the graph?

(a) Histogram

(b) Boxplot

(c) Stem-and-leaf plot

= 2. The geometric mean cannot be used when _______________.

= (a) a value is negative or zero

= (b) values reflect population growth

= (c) the arithmetic mean would not be close to the center values

= 3. Which one of the following characteristics does not apply to the correlation coefficient?

(a) It measures the strengt= h of linear association.

(b) It resistant to the out= liers.

(c) It is based on means and standard deviations of two variables.

= 4. Which of the following is the most useful in assessing the relationship between t= wo continuous variables?

(a) Stemplot

(b) Histogram

(c) Scatterplot

(d) Boxplot

= 5. The relative width of the bars has meaning for a ______________.

(a) bar graph

(b) histogram

(c) boxplot

= 6. When the standard deviation is expressed as percent of the mean, the result is called ______.

(a) the coefficient of vari= ation

(b) the coefficient of determination

(c) the signal to noise rat= io

= 7. If two distributions have exactly same mean and standard deviation, then their frequency curves are identical.

(a) True

(b) False

= 8. Which of the following is not a measure of variability?

(a) Range

(b) Standard deviation

= (d) Standard score

= 9. The crude death rate for a county in a state is 8.4 per 1000 and its age-adjust= ed death rate, using the state’s age distribution as the standard, is 9.7. From these we can infer = that the mean age of the county is _____________ the mean age of the state.

(a) greater than (older)

(b) smaller than (younger)<= /p>

(c) same as

= 10. If wo= men always married men who were 2 years older, then what would the correlation coefficient between the ages of husbands and wives?

(a) -1

(b) 0

(c) +1

= 11. The m= ean is _________ the median when a frequency distribution is positively skewed (to= the right).

(a) smaller than

(b) same as

(c) greater than

12. Which of the following has the same unit of measur= ement as the original observations?

(a) Variance

(b) Standard deviation

(c) Coefficient of variatio= n

= 13 The crude death rate can be obtained by taking a weighted mean of age-specific death rates, using its own population’s distribution as the weights.<= /p>

(a) True

(b) False

14. Meaningful comparisons of the variability of diffe= rent distributions can be based on ______.

(a) standard deviations

(b) ranges

(c) coefficients of variati= on

15. The proportion of males in a community is the same= as the arithmetic mean when the data are coded “1" for males and “0" for females.

(a) True

(b) False

16. A study reported correlation of 0.8 between the ge= nder of a worker and his or her income. = How would you interpret the correlation?

(a) Women are almost equall= y paid as men on the average.

(b) Women’s income is= 64% of men’s income on the average.

(c) The correlation makes n= o sense in this case.

17. If a population grows 1 percent each year, it woul= d take about ________ years to double = the population.

= (a) 70

= (b) 80

= (c) 90

= (d) 100

18. The Spearman correlation coefficient is appropriat= e for two variables that are measured by an ordi= nal scale.

= (a) True

= (b) False

**________=
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__Answers __=

1(c); 2(a); 3(b); 4(c); 5(b); 6(a); 7(b); 8(c); 9(b); 10(c);

11(c); 12(b); 13(a); 14(c); 15(a); 16(c); 17(a); 18(= a).