Biostats Week 7

Question 1

µ

Answer 1

Mu. Mean of a population or probability distribution

Question 2

t

Answer 2

1) a particular probability distribution or 2) a value that obeys that distribution

Question 3

z-score

Answer 3

s (standard deviation)

Question 4

s

Answer 4

standard deviation

Question 5

µ

Answer 5

mean

Question 6

σ

Answer 6

Sigma. Standard deviation of a population.

Question 7

m

Answer 7

Mean of a sample

Question 8

s^2

Answer 8

Sample variance

Question 9

n

Answer 9

Number of cases

Question 10

Median

Answer 10

score that divides a distribution in half; the mathematical midpoint

Question 11

Mode

Answer 11

The value that appears most often during the dataset

Question 12

Bimodal distribution

Answer 12

a distribution containing two numeric values that appear with equal frequency

Question 13

Variability

Answer 13

extent to which the scores are dispersed around the mean

Question 14

Range

Answer 14

difference between the highest and lowest values in a distribution

Question 15

Deviations from the mean

Answer 15

calculated by subtracting the mean from a given score; sum of the deviations will always equal zero

Question 16

Mean deviation

Answer 16

Sum of mathematically absolute deviations from the mean of the distribution

Question 17

Variance

Answer 17

equal to the standard deviation squared

Question 18

Standard deviation

Answer 18

Standard deviation: square root of the variance

s=standard deviation for sample, σ=standard deviation for a population

Question 19

Z/Z-score

Answer 19

Z (Z Score): point along the baseline of a standardized normal curve

Question 20

Hypothesis

Answer 20

Hypothesis: statement of expectations

Question 21

Null hypothesis

Answer 21

Null hypothesis: statement of equality; statement of no difference; statement of chance

Question 22

Critical value

Answer 22

Critical value: point on a distribution that marks the beginning of the critical region; point of comparison when making decision about null hypothesis

Question 23

Calculated test statistic

Answer 23

Calculated test statistic: result of a hypothesis-testing procedure; value that is compared to critical value

Question 24

Critical region

Answer 24

Critical region: portion of distribution that contains all the values that allow you to reject the null hypothesis; also known as region of rejection

Question 25

Type I Error

Answer 25

Type I error: rejection of the null hypothesis when it is in fact true

Question 26

Type II Error

Answer 26

Type II error: failure to reject the null hypothesis when it is false

Question 27

Single sample with sigma unknown

Answer 27

Single sample with sigma unknown: standard error of the mean is estimated and t is used

Question 28

Single sample with sigma known

Answer 28

Single sample with sigma known: standard error of the mean is calculated in a direct fashion and Z is used

Question 29

t-statistic

Answer 29

Used when we do not know the standard deviation of the population mean.

Question 30

How to calculate t

Answer 30

(Sample std dev/√(sample size))

Question 31

Matched samples (related):

Answer 31

Samples selected in such a way that cases included in one sample are related to cases in another (before & after sampling, etc)

Question 32

Standard error of mean difference:

Answer 32

Standard deviation of repeated sampling of mean differences between scores reflected in 2 samples

Question 33

A nurse researcher wishes to determine if there is a difference in the mean serum phosphorus level for a random sample of clients who have puritis and a random sample of clients who do not have puritis. What would be an appropriate test?

Answer 33

t-test for independent groups

Question 34

Your study includes an alpha of 0.05 and a power of 0.80. You conduct a student t-test, which has a large sample and a p-value of 0.04. What type of error might you make?

Answer 34

Type I

Question 35

In order to calculate the necessary sample size for your study you will need to know:

Answer 35

Effect size

Power

Question 36

You are asked to design a study determining whether there is a difference in the average fasting blood glucose for individuals with diabetes randomized either to a strictly dietary intervention or to a diet and exercise intervention. What are you investigating?

Answer 36

Difference

Question 37

If you select an alpha of 0.05 and a power of 0.80 for your study and your independent t-test for the difference in the mean serum potassium level of kidney dialysis patients and kidney transplant patients has a p-value of 0.02. You know this means:

Answer 37

There is a significant difference between the 2 groups

Question 38

Your study includes an alpha of 0.05 and a power of 0.80. You conduct a student t-test, which has a p-value of 0.07. What type of error might you make?

Answer 38

Type II

Question 39

How does effect size increase statistical power?

Answer 39

The smaller the effect size the more overlap between our distributions and the lower the statistical power.

Question 40

You conduct a study to determine if there is a difference in average number of hours slept each week between husbands and wives.What would be an appropriate test?

Answer 40

t-test for independent groups

Question 41

The following is a NONDIRECTIONAL hypothesis.

The relationships among gender identity, religiosity, and social actions are weaker among Arab women than among Jewish women.

Answer 41

FALSE

Question 42

You anticipate a large effect size in your study, therefore you will need a large sample size.

Answer 42

FALSE