WINTER BREAK REVIEW VOCAB

Question 1

What points have leverage in regression?

Answer 1

Those far to the left and right from x-bar

Question 2

What points are outliers in regression?

Answer 2

Those that don’t follow the flow.

Question 3

What points have influence in regression?

Answer 3

Those that would change the slope if removed (they are outliers that have leverage)

Question 4

Interpret r^2 ?

Answer 4

The percent of variablility in Y explained by the model with X

Question 5

Interpret y-intercept?

Answer 5

When X=0, the model predicts this much Y.

Question 6

Interpret SLOPE

Answer 6

For every 1 unit of x, there is a change of SLOPE units of y

Question 7

Find P( Z > 1.5) ?

Answer 7

normcdf( 1.5, 9999)

Question 8

Describe independence and association with quantitative examples.

Answer 8

Height and IQ are independent. Height and weight are associated.

Question 9

Describe independence and association with categorical examples.

Answer 9

Grade and pizzsa preference are independent, gender and gaming status are associated

Question 10

function to find area under normal curve?

Answer 10

normcdf

Question 11

function to find a percentile in normal model?

Answer 11

INVNORM

Question 12

What are the measures of spread we use?

Answer 12

standard deviation, variance, range, interquartile range, standard error

Question 13

What are the measures of center we use?

Answer 13

mean, median, mode

Question 14

How do you describe the distribution of a single data set? (a histogram)?

Answer 14

SHAPE (#modes, skewness), CENTER (measure of center), SPREAD (measure of spread), STRANGE (outliers or gaps)

Question 15

How do you describe an association between two quantitative variables? (scatter plot)

Answer 15

DIRECTION (pos/neg) FORM (linear,curved) STRENGTH (strong, moderate, report “r” value)

Question 16

What does rSy/Sx mean?

Answer 16

slope formula. For each SD in X, you go r SD in y

Question 17

What does SD of residuals tell us?q

Answer 17

Average distance to the model. About how far off we expect model to be.

Question 18

What graphs for QUANTITATIVE data?

Answer 18

histogram, box/whisker, stemplot, dot plot, ogive, time plot, line graph

Question 19

What graphs for CATEGORICAL data?

Answer 19

segmented bar, bar, pie, mosaic

Question 20

Diff between standard deviation and standard error?

Answer 20

Standard deviation is typical distance to mean for a data point, Standard error is typical distance to parameter for a statistic in a sampling distribution.

Question 21

What is variance?

Answer 21

A measure of spread- the average squared distance to the mean. SD^2

Question 22

What is a Z score?

Answer 22

the number of SD a data value is away from the mean

Question 23

What is a test statistic?

Answer 23

The number of SE a statistic is away from the hypothesized parameter.

Question 24

What is formula for nCr ?

Answer 24

n! / r! (n-r) !

Question 25

What is margin of error?

Answer 25

Distance you reach up and down when making CI. It is CRIT * SE

Question 26

What is error?

Answer 26

Distance from a statistic to the parameter. How far off your stat is from the truth.

Question 27

What is a confidence interval?

Answer 27

A parameter catcher. It tries to catch the truth.

Question 28

What does “95% confident” mean?

Answer 28

If you took 100 samples and made 100 confidence intervals, about 95 would contain the parameter and about 5 would not.

Question 29

What is alpha?

Answer 29

It is the rejection threshold. Reject Ho when p-value is below alpha.

Question 30

What is a p-value?

Answer 30

The likelihood you obtained your statistic or one more extreme due to just chance if the Null was actually true.

Question 31

Suppose p value = 0.003. How would you interpret?

Answer 31

With a p-value this low (0.003 < 0.05), I reject the Ho, there is enough evidence to say [Ha in context]

Question 32

What are the the sample size requirements for inference for both means and proportions?

Answer 32

1. You need a random sample. 2. (not too big) Less than 10% of population 10n30. For props, np>10 and nq>10.

Question 33

Minimum sample size for means?

Answer 33

If population is normalish, then there is no minimum sample size. If it is skewed or bimodal or any other non-normal distribution, then n>30.

Question 34

Minimum sample size for proportions?

Answer 34

You need at lease 10 successes, np>10, and 10 failures, nq > 10

Question 35

What is the golden sentence?

Answer 35

I was curious about a population paramter, but a census was too costly so instead I took a sample and used the data to calculate a statistic and then made an inference about the parameter with that statistic.

Question 36

What is probability?

Answer 36

Long run relative frequency. (the long run percent)

Question 37

What is the Law of Large Numbers?

Answer 37

In the long run, after many many trials, the % of successes approaches the true probability. Think: if you flip a coin twice, you may get 0% heads, 50% heads or 100% heads. If you flip 10,000 times, you probably will have about 50% heads (def not 0 or 100)

Question 38

What is a critical value?

Answer 38

1 for 68% confidence, 2 for 95 and 3 for 99.7. It is the number of SE you want to reach out in a confidence interval.

Question 39

Where are outliers located in a data set ?

Answer 39

outside the fences. Lower Q1-1.5IQR and upper Q3+1.5IQR

Question 40

What is a sampling distribution?

Answer 40

A pile of statistics taken from many many many samples

Question 41

What are the two sampling distributions we have discussed?

Answer 41

MEANS: N ( mu, sigma/root n) and PROPORTIONS: N ( p, root (pq/n) )

Question 42

When we combine random variables, what do we add?

Answer 42

Add means and add variances. DO NOT ADD ST DEV. You add variances and take the square root of the sum to find combined SD.