Topic 1: Statistical Inference

Question 1

parameter

Answer 1

a property or number descriptive of the population

Question 2

statistic

Answer 2

• a property or number descriptive of a sample
• often used to estimate an unknown -parameter

Question 3

nominal

Answer 3

classifies/identifies objects

Question 4

ordinal

Answer 4

ranking data (distances are not the same)

Question 5

interval

Answer 5

rating data (equal distances)

Question 6

ratio

Answer 6

a special kind of interval with a meaningful zero point

Question 7

univariate

Answer 7

• one DV, can have multiple IVs
• linear regression

Question 8

multivariate

Answer 8

multiple DVs, regardless of the # of IVs

Question 9

z-scores

Answer 9

transforms any normal distribution into the standard normal distribution where mean = 0 & standard deviation = 1

Question 10

statistical inference

Answer 10

a process to conclude a population from data on selected individuals

Question 11

two types of statistical inference

Answer 11

tests of significance & CIs

Question 12

central limit theorem (CLT)

Answer 12

as n increases, the distribution of the sample mean becomes closer to a normal distribution

Question 13

NHST

Answer 13

1. state the null & alternative hypotheses
2. calculate the value of an appropriate test statistic
3. find the p-value of the observed data
4. state a conclusion

Question 14

small effect

Answer 14

r2 = 0.01, r = 0.1, d = 0.25

Question 15

medium effect

Answer 15

r2 = 0.06, r = 0.3, d = 0.5

Question 16

large effect

Answer 16

r2 = 0.15, r = 0.5, d = 0.8

Question 17

type l error

Answer 17

reject H0 when it’s true (false +)

Question 18

type ll error

Answer 18

retain H0 when it’s false (false -)

Question 19

a

Answer 19

probability of committing a type l error

Question 20

b

Answer 20

probability of committing a type ll error

Question 21

1-b

Answer 21

power: the probability of correctly rejecting a false H0

Question 22

purpose of z-test

Answer 22

to test whether a sample mean differs from a population mean

Question 23

assumptions of z-test

Answer 23

1. the population is normally distributed
2. the population standard deviation must be known
3. independence of observation (simple random sample of the population)

Question 24

limitation of z-test

Answer 24

we rarely know the population standard deviation

Question 25

purpose of t-test

Answer 25

to test whether a sample mean differs from a population mean

Question 26

assumptions of t-test

Answer 26

1. the population is normally distributed
2. independence of observation (simple random sample of the population)

Question 27

t-distribution

Answer 27

varies in shape according to df = n01

Question 28

p-value

Answer 28

assuming H0 is true, the probability of obtaining a test statistic equal to or more extreme than what was observed from a given sample

Question 29

sampling distribution

Answer 29

the distribution of values taken by the statistic in all possible samples of size N from the same population

Question 30

the shape of the sampling distribution

Answer 30

The shape of the distribution of the sample mean depends on the shape of the population.

Question 31

effect size

Answer 31

a standardized measure of the magnitude of a treatment effect

Question 32

common types of effect size measures

Answer 32

• Pearson’s correlation coefficient (r) or correlation ratio squared (r²)
• Cohen’s d
• Omega (ω) or omega squared (ω²)