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Question 1

Cross-sectional Data

Answer 1

comparing different entities in a reference point (period of time)

Question 2

Time-series Data

Answer 2

data collected over several time periods

Question 3

Panel Data

Answer 3

cross-sectional time-series data

Question 4

Data Sources

Answer 4

experiments, A-B testing (includes split testing)

Question 5

A-B Testing

Answer 5

comparing two versions of something

Question 6

Observation

Answer 6

no manipulation of variables

Question 7

Relative Frequency Distributions, in what form are the frequencies represented?

Answer 7

Fractions

Question 8

Left Skew

Answer 8

tail is on the left

Question 9

Right Skew

Answer 9

tail is on the right

Question 10

sample mean equation

Answer 10

sum all values / num of values

Question 11

population mean equation

Answer 11

sum all values / num of values

Question 12

variance equation

Answer 12

sum((x - mean)^2)/(n-1)

Question 13

standard deviation equation

Answer 13

root[sum((x - mean)^2)/(n-1)]; variance rooted

Question 14

Coefficient of Variation Equation

Answer 14

(standard deviation / mean)*100; expressed as a percent

Question 15

Calculate value for IQR

Answer 15

(n + 1)(IQR)
ex: (n+1)(0.25)
when its not a full number take the difference between closest values and multiply by double - int
when IQR = 2.25
(8-7)*0.25 + 7

Question 16

z score standardization

Answer 16

(x - mean) / STD

Question 17

Empirical Rule

Answer 17

Normal Distribution:
-1 STD < x < 1 STD is 68%
-2 STD < x < 2 STD is 95%
-3 STD < x < 3 STD is 99.7%

Question 18

Covariance meaning

Answer 18

positive > positive relationship
negative > negative relationship; comparison across different graphs is meaningless.

Question 19

Correlation Coefficient

Answer 19

• R
• between -1 and 1

Question 20

coefficient of determination

Answer 20

• R^2
• between -1 and 1
• comparable across graphs
• SSR/SST