Benchmark info

Question 1

describe statistics

Answer 1

the science of developing methods for collecting, analyzing, interpreting, and presenting data

Question 2

what is the main goal of statistics

Answer 2

to use information from a sample to make inferences about the population

Question 3

what is a variable?

Answer 3

a measurable attributs that can vary across entities and is represented by a column

Question 4

what is an observation?

Answer 4

the complete set of recorded values for each entity, typically encapsulated in a single row of dataset

Question 5

what is correlation?

Answer 5

it measures the association between two variables

Question 6

when should you use mean and how is it affected by outliers?

Answer 6

• use with symmetric distributions without extreme values
• mean is highly sensitive to outliers

Question 7

when should you use median and how is it affected by outliers?

Answer 7

• use for skewed distributions or data with outliers
• median is less affected bu outliers

Question 8

when should you use mode and how is it affected by outliers?

Answer 8

• use when identifying the most common category or score
• mode is not influenced by outliers

Question 9

what is variance in technical terms?

Answer 9

• the average of the squared differences from the mean
• the square of the standard deviation

Question 10

what statistical tests can be used to find outliers?

Answer 10

z-score and IQR

Question 11

describe histograms

Answer 11

• displays continuous data
• has touching bars representing frequency across intervals

Question 12

what does skewness measure?

Answer 12

measure asymmetry of distribution

Question 13

what does kurtosis measure?

Answer 13

“tailedness” or sharpness of the peak of a distribution

Question 14

describe a scatterplot

Answer 14

displays the relationship between two numerical variables

Question 15

what are “measures”?

Answer 15

• quantitative way of representing or summarizing aspects of data
• tools used to describe, analyze, and make sense of data

Question 16

what is internal consistency?

Answer 16

the extent to which different items that are trying to measure the same variable are truly related and report similar results

Question 17

what is construct validity?

Answer 17

whether the test accurately measures the underlying theoretical concept it is trying to measure

Question 18

what is content validity?

Answer 18

whether the test covers all the important aspects of that construct

Question 19

what is criterion-related validity?

Answer 19

how well one measure (predictor) correlates with a related outcome measure (the criterion) that is considered an established standard or a relevant benchmark

Question 20

what is a null hypothesis?

Answer 20

a statement that claims there is NO difference, NO effect, NO relationship between variable

Question 21

what is a type I error?

Answer 21

rejecting the null hypothesis when it is true

Question 22

what is type II error?

Answer 22

failing to reject the null hypothesis when it is false

Question 23

describe symbol, meaning, and interpretation of significance level

Answer 23

• α
• probability of making a type I error
• risk of false positive

Question 24

describe symbol, meaning, and interpretation of confidence level

Answer 24

1-α
- prbability of not making type I error
- certainty in correctly accepting a true null hypothesis

Question 25

describe symbol, meaning, and interpretation of type II error rate

Answer 25

β
- probability of making type II error
- risk of a false negative

Question 26

when do you reject the null hypothesis?

Answer 26

when your statistic is larger than your critical value

Question 27

what is a critical value?

Answer 27

a threshold that defines the boundary of a statistical test’s rejection region

Question 28

what is another name for the normal distribution?

Answer 28

Gaussian distribution

Question 29

does the normal distribution curve ever touch the horizontal axis?

Answer 29

no

Question 30

what is the purpose of a t-test?

Answer 30

to see if there is a significant difference between means or populations

Question 31

what is the purpose of an ANOVA?

Answer 31

to test for significant differences between 3 or more groups

Question 32

what is a factorial ANOVA used for?

Answer 32

to test for the effects of two or more independent variables (factors) on a dependent variable

Question 33

what does the number of factors in an ANOVA indicate?

Answer 33

the number of factors indicates the number of main effects

Question 34

what is the purpose of correlation?

Answer 34

it measures the direction and strength of a linear relationship between two variables

Question 35

what does the p-value of a correlation tell you?

Answer 35

the probability of observing a correlation at least as extreme as the calculated coefficient (assuming there is no actual correlation)

Question 36

what are the limitations of correlation?

Answer 36

• sensitive to outiers
• curvilinear relationships (correlation can only measure linear relationships)
• restriction of range

Question 37

what are the two uses of a chi-squared test?

Answer 37

1) test for indepndence
2) test for goodness of fit

Question 38

what kind of data is typically used with a chi-squared test?

Answer 38

catagorical data

Question 39

what is Y-hat in linear regressions?

Answer 39

the predicted value of Y

Question 40

what are residuals in linear regressions?

Answer 40

observed value - predicted value

Question 41

what does R-squared represent in linear regression?

Answer 41

how well the independent variable exaplains the variance in the dependent variable