Computer based biostatistics

Exercises 3.1, 3.3, 3.4, and 3.7 (pages 44-45)

3.1

Find , s, V, and the median for the following data (mg of glycerine per mg of creatinine in the urine of 37 chimpanzees: from Gartler, Firschein, and Dobnzhansky, 1956).

 

(Use “Data_Exercise 3.1.txt”)

 

3.3

The following are percentages of butterfat from 120 registered three-year-old Ayrshire cows selected at random from a Canadian stock record book.

• Calculate , s, and V directly from the data.
• Group the data in a frequency distribution and again calculate Y, s, and V. Compare the results with those of (a). How much precision has been lost by grouping? Also calculate the median.

 

(Use “Data_Exercise 3.3.txt”)

 

3.4

What effect would adding a constant 5.2 to all observations (from 3.3) have upon the numerical values of the following statistics: , s, V, average deviation, median, mode range? What would be the effect of adding 5.2 and then multiplying the sums by 8.0? Would it make any difference in the above statistics if we multiplied by 8.0 first and then added 5.2?

 

(Use “Data_Exercise 3.3.txt”)

 

3.7

Using the striped bass age distribution given in Exercise 2.9, compute the following statistics: , s², s, V, median, and mode.

 

(Use “Data_Exercise 2.9.txt”)

 

Exercises 5.8 and 5.9 (page 92)

5.8

Perform a graphical analysis on the following measurements. Are they consistent with what one would expect in sampling from a normal distribution?

 

(Use “Data_Exercise 5.8.txt”)

 

5.9

The following data are total lengths (in cm) of bass from a southern lake.

• Computer the mean, the standard deviation, and the coefficient of variation.
• Make a histogram of the data.
• Do the data seem consistent with a normal distribution on the basis of a graphic analysis? If not, what type of departure is suggested?

 

(Use “Data_Exercise 5.9.txt”)

 

Exercises 6.2, 6.3, 6.4, 6.5, and 6.6 (page 131)

 

6.2

Differentiate between type I and type II errors. What do we mean by the power of a statistical test?

 

6.3

Set 99% confidence limits to the mean, median, coefficient of variation, and variance for the birth weight given in Box 3.2

 

(Use “Data_Box 3.2.txt”)

 

6.4

The 95% confidence limits for mu as obtained in a given sample were 4.91 and 5.67 g. Is it correct to say that 95 times out of 100 the population mean mu falls inside the interval from 4.91 to 5.67 g? If not, what would the correct statement be?

 

6.5

In a study of mating calls in the tree toad Hyla ewingi, Littlejohn (1965) found the note duration of the call in a sample of 39 observations from Tasmania to have a mean of 189 msec and a standard deviation of 32 msec. Set 95% confidence intervals to the mean and to the variance.

 

6.6

Set 95% confidence limits to the means listed in Table 6.2. Are these limits all correct? (That is, do they contain mu?)

 

(Use data from page 100)