Biostatistics lecture 1

Question 1

Probability experiment is:

Answer 1

A. a process whose final outcome is unknown

Question 2

Event opposite to event A:

Answer 2

B. includes all events which belong to the sample space and do not belong to event A

Question 3

Elementary event is:

Answer 3

B. a single possible outcome of a probability experiment

Question 4

The litter consists of 2 males and 8 females. The probability of picking a female when one individual is selected:

Answer 4

D. 0.8

Question 5

Probability of event A [P(A)] is 0.5 and event B [P(B)] is 0.2. Events are independent. Probability both occur:

Answer 5

A. P(A) × P(B) = 0.1

Question 6

There are 4 rooms and 4 animals (1 per room). How many combinations possible?

Answer 6

C. 24

Question 7

Alpha (α) stands for:

Answer 7

A. the level of significance

Question 8

CI 99% stands for:

Answer 8

A. confidence interval for the 99% level of confidence

Question 9

1000 cows were randomly selected… Their mean daily milk yield is 40 kg (CI 95%: 36 to 44 kg). This means:

Answer 9

B. population mean is at least 95% likely between 36 and 44 kg

Question 10

Parametric tests (e.g. Student’s t-test) are used for comparing:

Answer 10

C. arithmetic means between groups

Question 11

Wilcoxon signed rank test, p = 0.061. Conclusion (α = 0.05):

Answer 11

B. no grounds to reject null hypothesis

Question 12

Wilcoxon signed rank test, p = 0.049. Conclusion (α = 0.05):

Answer 12

D. null hypothesis should be rejected

Question 13

Null hypothesis (H₀) always states:

Answer 13

B. no significant difference

Question 14

Which point includes paired samples?:

Answer 14

B. horse temperature before and after race

Question 15

Median is a measure of central tendency which can be used for describing:

Answer 15

A. numerical data and categorical data in ordinal scale

Question 16

Standard deviation (SD) is:

Answer 16

B. the classical measure of dispersion (spread)

Question 17

Best measure of central tendency for horse ages: 2.2, 2.7, 3.1, 4.3, 5.4:

Answer 17

B. arithmetic mean

Question 18

Mode for data set: 2, 2, 3, 4, 5, 7, 9, 12, 12 is:

Answer 18

D. 2 and 12

Question 19

The 2nd quartile is always equal to:

Answer 19

C. the median

Question 20

Coefficient of concentration (kurtosis):

Answer 20

C. is positive when data distribution is leptokurtic

Question 21

If data have left-hand asymmetric distribution:

Answer 21

D. median > arithmetic mean

Question 22

In asymmetrically distributed data:

Answer 22

C. median is a better measure of central tendency than the arithmetic mean