Exam Review Units 1-6

Question 1

What’re individuals?

Answer 1

individuals are objects described by a set of data

Question 2

What’re variables?

Answer 2

variables are any characteristic of an individual

Question 3

What’re categorical variables?

Answer 3

categorical variables are qualitative

Question 4

What’er quantitative variables?

Answer 4

quantitative variables are numerical

Question 5

What’s an outlier?

Answer 5

An outlier is an individual observation that falls outside the overall pattern of the data.

Question 6

What’s nonresistance?

Answer 6

nonresistance is when extreme observations impact the value.

Question 7

Examples of nonresistance?

Answer 7

mean and standard deviation

Question 8

How can you display distributions with graphs?

Answer 8

displaying distributions with graphs:

1. dotplots
2. histograms
3. stemplots
4. time plots
5. bar graphs

Question 9

How to describe distributions with numbers? (important)

Answer 9

describing distributions with numbers:

1. measures of center: mean, median, and mode
2. measures of spread: range, interquartile range, standard deviation
3. measuring position: quartiles, percentiles

Question 10

What’s percentile?

Answer 10

percentile is the percent of the distribution that is at or to the left of the observation.

Question 11

What does the normal distribution look like? (4) (important)

Answer 11

normal distribution:

1. symmetric
2. one peak
3. bell shaped
4. described by its mean and standard deviation.

Question 12

What does the 68-95-99.7 rule apply to?

Answer 12

68-95-99.7 rule applies to NORMAL DISTRIBUTIONS.

Question 13

What’s the 68-95-99.7 rule?

Answer 13

68-95-99.7 rule:

1. 68% of the observations fall within 1 standard deviation of the mean
2. 95% of the observations fall within 2 standard deviations of the mean
3. 99.7% of the observations fall within 3 standard deviations of the mean

Question 14

How to determine if data is normal?

Answer 14

1. for histograms, stemplots, and box plots: look for a bell shape
2. for normal probability plots: look for a straight line.

Question 15

What’s a parameter?

Answer 15

a parameter is a number that describes the population.

Question 16

Do we know the parameters?

Answer 16

NO! WE do not

Question 17

what’s a statistic?

Answer 17

a statistic is a number that we can find using the sample data without using unknown parameters.

Question 18

What do we use a statistic for?

Answer 18

we use a statistic to estimate the unknown parameter

Question 19

what’s the sampling distribution?

Answer 19

the sampling distribution is the distribution of values taken by a statistic in all possible samples of the samite size from a population.

Question 20

When is a statistic unbiased?

Answer 20

a statistic is unbiased if the mean of its sampling distribution is equal to the true value of the parameter you’re estimating.

Question 21

What’s the variability of a statistic?

Answer 21

the variability of a statistic is the SPREAD of its SAMPLING DISTRIBUTION.

Question 22

What determines the spread of a sampling distribution?

Answer 22

These determine the spread of a sampling distribution:

1. sampling design
2. size of the sample

Question 23

How does sample size affect the spread?

Answer 23

as the sample size increases, the spread decreases and becomes smaller.

Question 24

When does the margin of error of a confidence interval get smaller? (3)

Answer 24

the margin of error of a confidence interval gets smaller when:

1. the confidence “C” level decreases
2. the population standard deviation decreases
3. the sample size “n” increases.

Question 25

Why do you do a test of hypothesis?

Answer 25

you do a test of hypothesis to assess the evidence provided by data against a null hypothesis H0 in favor of an alternative hypothesis Ha.

Question 26

For hypothesis tests of significance, what’s H0?

Answer 26

H0 is the null hypothesis

Question 27

For hypothesis tests of significance, what’s Ha?

Answer 27

Ha is the alternative hypothesis

Question 28

What’s a test of significance based on?

Answer 28

a test of significance is based on a TEST STATISTIC.

Question 29

What’s the p-value?

Answer 29

the p-value is the probability that the test statistic will take a value at least as extreme as the observed value if the NULL H0 is TRUE.

Question 30

What do small p-values tell you?

Answer 30

small p-values tell you indicate strong evidence against the null hypothesis H0.

Question 31

What happens if the p-value is equal to or less than the alpha “a”?

Answer 31

if the p-value is equal to or less than the alpha “a,” the data are STATISTICALLY SIGNIFICANT at the alpha “a” significance level

Question 32

When’s the data STATISTICALLY SIGNIFICANT at the alpha “a” significance level?

Answer 32

the data is STATISTICALLY SIGNIFICANT at the alpha “a” significance level when the p-value is less than or equal to alpha “a.”

Question 33

What’s a type 1 error? (important)

Answer 33

a type 1 error is when we reject the null hypothesis H0 when it is TRUE.

Question 34

What’s a type 2 error? (important)

Answer 34

a type 2 error is when we accept the null hypothesis H0 when in fact the alternative hypothesis Ha is true.

Question 35

What’s the power of a significance test?

Answer 35

The power of a significance test measures its ability to detect an alternative hypothesis

Question 36

What’s the power against a specific alternative?

Answer 36

the power against a specific alternative is the probability that the test will reject the null H0 when the alternative is true.

Question 37

In a fixed level alpha “a” test, what’s the level alpha “a”?

Answer 37

In a fixed level alpha “a” test, the level alpha “a” is the probability of a TYPE ONE (1) error

Question 38

In a fixed level alpha “a” test, what’s the power against a specific alternative?

Answer 38

In a fixed level alpha “a” test, the power against a specific alternative is 1 - beta “b”
- beta is the probability of a Type TWO (2) error

Question 39

In a fixed level alpha “a” test, what’s the level beta “b”?

Answer 39

In a fixed level beta “b” test, the level beta “b” is the probability of a TYPE TWO (2) error

Question 40

What’s the standard error of a statistic?

Answer 40

The standard error of a statistic is the standard deviation of a statistic you estimate from the data.

Question 41

When do you use a T Distribution?

Answer 41

you use a T distribution when you don’t know the population’s standard deviation σ.