W1 EXPLAINING AND PREDICTING THE WORLD

Question 1

What are the 3 central tendencies?

Answer 1

Mean, Median, Mode

Question 2

What is VARIANCE?

Answer 2

Average squared deviation from the mean

Question 3

What is the variance of this set? {1,2,3,4,5} (Population)

Answer 3

Variance 1. Get mean (3) 2. For i in nums: total += (mean - nums[i])^2 total / len(nums) Variance = 10/5 variance = 2

Question 4

What is the formula for Variance?

Answer 4

SUM[i-n] (y[i] - μ)^2 / n

Question 5

What is the formula for Variance in a sample?

Answer 5

SUM[i-n] (y[i] - μ)^2 / (n - 1)

Question 6

What is the formula for standard deviation?

Answer 6

√(SUM[i-n] (y[i] - μ)^2 / n)

Question 7

What is σ and μ?

Answer 7

Standard Deviation and Mean

Question 8

How to calculate Coefficient of variation?

Answer 8

CV = σ/μ x 100

Question 9

What skew does this graph have?

Answer 9

Positive

Question 10

What skew does this graph have?

Answer 10

Negative

Question 11

What is kurtosis?

Answer 11

Kurtosis is a measure of whether the data are heavy-tailed or light-tailed relative to a normal distribution.

Question 12

What is Mesokurtic?

Answer 12

A normal amplitude for a normal distribution curve

Question 13

What is Leptokurtic?

Answer 13

A higher amplitude for a normal distribution curve

Question 14

What is Platykurtic?

Answer 14

A shallower amplitude for a normal distribution curve

Question 15

What are the approximate % within each standard deviation?

Answer 15

μ to 1σ: 34.1% 1σ to 2σ: 13.6% 2σ to 3σ: 2.1% 3σ to 4σ: 0.1%

Question 16

What is the the null hypothesis?

Answer 16

A statement about a population parameter (e.g., population mean) that is assumed to be true. Where we start, and what we aim to falsify.

Question 17

What is the alternative hypothesis?

Answer 17

Statement that directly contradicts the null hypothesis by stating that the actual value of a population parameter is less than, greater than, or not equal to the value stated in the null hypothesis. Hypothesis we are trying to prove.

Question 18

How much significance is required to reject the null?

Answer 18

Usually 5%, but 1% and .5% depending on what it is. So long as you can justify your significance level.

Question 19

What are one-tailed/two-tailed tests?

Answer 19

One tailed only counts one direction of the normal dist, and two tailed counts both.

Question 20

What is a p-value?

Answer 20

A probability to compare to the significance level. Usually 0.05. A p-value is the probability of obtaining an effect at least as extreme as the one in your sample data, assuming the truth of the null hypothesis.

Question 21

What would a p-value of 0.03 mean?

Answer 21

A p-value of 0.03. This P value indicates that if the intervention had no effect, we would obtain the observed difference or more in 3% of studies (because of sampling error)

Question 22

What is the Type I error

Answer 22

When the researcher rejects the null hypothesis when it is actually true

Question 23

What is the Type II error

Answer 23

When the researcher accepts the null hypothesis when it is actually false

Question 24

What is POWER in hypothesis testing?

Answer 24

The probability of rejecting a null hypothesis that’s actually false. 1 - β