Task 6

Question 1

What are the assumptions of a z-test for 1 proportion?

Answer 1

• Variable = categorical and dichotomous

- Normality

Question 2

What assumption is always violated for a z-test for 1 proportion?

Answer 2

normality therefore ensure samples are large enough -> CLT

Question 3

What is the Ho of a z-test for 1 proportion?

Answer 3

Ho: π = πo (i.e. population proportion equals a certain value

Question 4

What is the unbiased estimator in a z-test for 1 proportion?

Answer 4

sample proportion (p aka p^)

Question 5

How do we find the standard deviation involved in a z-test for 1 proportion?

Answer 5

If we know the mean proportion then we automatically know the standard deviation (simple- if you know one proportion you know the others since we have 2 so you can draw the distribution in a bar chart )

Question 6

How to calculate the standard deviation of a z-test for 1 proportion?

Answer 6

top line of standard error formula

Question 7

How do you calculate a sample proportion?

Answer 7

p = x/n e.g. = 0.14 -> 14%

Question 8

What is the z-test for a population of 1 proportion?

Answer 8

p - πo / SE

Question 9

How to find a confidence interval for a z-test of 1 proportion?

Answer 9

p +- z* (SE)

-> In SE formula use sample proportion to estimate

Question 10

What are the assumptions for a z-test with 2 proportions?

Answer 10

• dependent and independent variables = categorical
• normality
• groups are independent

Question 11

What is the Ho of a z-test with 2 proportions?

Answer 11

Ho: π - πo

Question 12

How to calculate z-test for 2 proportions?

Answer 12

p1 - p2 / SE

Question 13

What is the most efficient estimator of the population proportion?

Answer 13

weighted average

x1+x2 / n1+n2

Question 14

What is the expected counts rule for X^2 goodness of fit test?

Answer 14

all counts in the frequency table must = 5 and taken together = 20

Question 15

Why is X^2 goodness of fit non-parametric?

Answer 15

It doesn’t use parameters

Question 16

What is the Ho of a X^2 goodness of fit?

Answer 16

follow known a distribution (25% 50% 25%

Question 17

Is the Ha of X^2 of goodness of fit?

Answer 17

two-tailed, does not follow distribution or no association

Question 18

How do you calculate expected counts?

Answer 18

N x πi

Question 19

What is the Ho of X^2 for contingency tables?

Answer 19

there is no association between the 2 variables x and y

Question 20

X^2 for contingency tables aka

Answer 20

X^2 for independence

Question 21

Expected counts assumption for X^2 for contingency tables

Answer 21

are at least = 5

Question 22

Why does the normality assumption not apply to X^2 tests?

Answer 22

it is non-parametric!

Question 23

What is the difference between the 2 X^2 tests in relation to variables?

Answer 23

X^2 for contingency tables -> 2 categorical variables

X^2 for goodness of fit -> 1 categorical variable