EXAM REVIEW

Question 1

quantitative variable

Answer 1

one that takes on a numerical value for a measured or counted quantity

Question 2

categorical/qualitative variable

Answer 2

one of a limited, usually fixed number of possible values

Question 3

discrete variable

Answer 3

a quantitative variable that takes a fixed set of possible values with gaps between

Question 4

continuous variable

Answer 4

a quantitative variable that can take any value in a interval on the number line

Question 5

relative frequency

Answer 5

the proportion or % of times a value occurs out of the total # of observations

Question 6

basic parameters for describing distribution

Answer 6

Context, shape(skew, uni vs bimodal), center(mean/median), variability(range, IQR or stdev) and outliers

Question 7

The mean is ___ than the median if the distribution has a right skew, The mean is __ than the median if the distribution has a left skew.

Answer 7

greater than, less than

Question 8

IQR

Answer 8

the distance between the 1st and 3rd quartiles of a distribution(Q3-Q1)

Question 9

1.5 x 1QR rule for outliers

Answer 9

outliers < Q1-(1.5IQR); outliers > Q3 + (1.5IQR)

Question 10

z-score equation

Answer 10

x-mean/stdev

Question 11

No pattern in a residual plot indicates that:

Answer 11

a linear model is appropriate

Question 12

least squares regression line equation

Answer 12

y= a + bx

Question 13

coefficient of determination(r^2)

Answer 13

proportion of the response variable variation the can be explained by the explanatory variable

Question 14

correlation coefficient(r)

Answer 14

measure direction and strength of association; always between -1 and 1

Question 15

r equation(using least square regression line equation)

Answer 15

b=r(stdev y/stdev x)

Question 16

census

Answer 16

A study that collects data from every individual in the population.

Question 17

cluster sample

Answer 17

The population is split into groups (clusters), and entire clusters are randomly chosen to be surveyed.

Question 18

simple random sample

Answer 18

A sample where every individual and group has an equal chance of being selected.

Question 19

stratified sample

Answer 19

The population is split into strata (groups) based on a shared trait, and a random sample is taken from each group.

Question 20

systematic random sample

Answer 20

Choose a random starting point, then select every nth person from a list.

Question 21

What are the 3 main types of bias?

Answer 21

voluntary, under-coverage and nonresponse bias

Question 22

matched pairs design

Answer 22

Subjects are paired based on similarity; each pair gets different treatments, or one subject gets both treatments in random order.

Question 23

experimental units

Answer 23

The individuals or items that receive treatments in an experiment.

Question 24

completely randomized design

Answer 24

All experimental units are randomly assigned to treatment groups, with no grouping beforehand.

Question 25

what is ‘blocking’ in a study?

Answer 25

Subjects are grouped by a variable (like age), and random assignment to treatments is done within each group.

Question 26

sample space

Answer 26

list of all possible outcomes

Question 27

joint probability

Answer 27

P(A and B) if = 0; events are disjoint

Question 28

probability addition rule(can be used to test if two events are mutually exclusive)

Answer 28

P(A U B): P(A) + P(B) - P(A and B) if = 0; exclusive

Question 29

conditional probability

Answer 29

probability of an event occurring, given that something has already happened P(A|B)= P(A and B)/P(B)

Question 30

the expected probability is found by:

Answer 30

adding the products of the amounts and their probabilities

Question 31

binomial variable

Answer 31

count successes in a fixed number of trials

Question 32

geometric variable

Answer 32

model the number of trials until the first success

Question 33

critical value used a 90%, 95% and 99% CI

Answer 33

1.645, 1.96, and 2.576 respectively

Question 34

3 "checks" for a proportion

Answer 34

1) Random 2) Normality(LC): np >= 10/ n(1-p) >= 10 3) 10% condition

Question 35

As sample size increases...

Answer 35

confidence interval decreases, but center remains constant

Question 36

Margin of error x 2 =

Answer 36

width of confidence interval

Question 37

Confidence interval statement

Answer 37

We are ___% confident that the proportion/mean of ___ is between ___ and ___.

Question 38

z-test equation for proportions

Answer 38

sample proportion-population/ stdev

Question 39

The null hypothesis is accepted when...

Answer 39

The statistic is greater than the alpha level

Question 40

Type I vs Type II error

Answer 40

Type 1: false positive Type 2: false negative

Question 41

power

Answer 41

1- Probability of making a Type II error

Question 42

interpreting p-value

Answer 42

If the null hypothesis were true, the probability of observing a proportion/mean/chi-squared value of at least ____ is ____(p-value).

Question 43

What is the difference between a matched pairs vs two-sample t-test?

Answer 43

A two-sample t-test compares the means of two independent groups, while a matched pairs t-test compares the means of two related groups

Question 44

different types of chi^2 tests

Answer 44

Gof: 1 sample, 1 variable Homogeneity: 2 samples, 1 variable Independence: 1 sample, 2 variables acronym: HIG H is the oldest(21); I is the middle(12); G is the youngest(11)

Question 45

what contributes most to the chi-square test statistic?

Answer 45

the observed count farthest away from the expected count