Statistics and Mechanics

Question 1

what do you include when commenting on data?

Answer 1

measure of location and spread

Question 2

how do you make an estimate within data?

Answer 2

with a regression line

Question 3

what is H0 and H1?

Answer 3

H0 is the hypothesis that you assume to be true. H1 is the opposite.

Question 4

what happens to the significance level with a two tailed test?

Answer 4

it is split between the two tails.

Question 5

how do you find that two events are independent?

Answer 5

P(a and b) = P(a)*P(b)

Question 6

what is the difference between y on x and x on y regression lines?

Answer 6

y on x reduces vertical deviation from the line (residuals) and x on y reduces horizontal deviation

Question 7

what is a causal relationship between data?

Answer 7

if one changes, the other changes too

Question 8

what things have to be true to have a binomial distribution?

Answer 8

fixed number of trials (n)
two possible outcomes
fixed probability of success
independent trials

Question 9

what is P(A|B)?

Answer 9

P(A∩B) / P(B)

Question 10

what are the points of inflection on the normal distribution graph?

Answer 10

μ ± σ

Question 11

what is a census?

Answer 11

every member of a population observed

Question 12

what is stratified sampling?

Answer 12

population is divided into mutually exclusive groups such as males and females and a random sample is taken from each

Question 13

what is systematic sampling?

Answer 13

every Nth member is observed

Question 14

what is opportunity sampling?

Answer 14

measuring members of the population available at the time

Question 15

what is quota sampling?

Answer 15

population is divided into groups. individuals are chosen from each to represent the entire population.

Question 16

what is the equation for standard normal distribution?

Answer 16

Z = (X-μ) / σ

Question 17

how do you convert binomial distribution to normal distribution under the right conditions?

Answer 17

μ = np
σ^2 = npq

Question 18

how is X̄ normally distributed?

Answer 18

X̄ ~ N (μ, σ^2 / n)

Question 19

what is the explanatory variable?

Answer 19

independent variable

Question 20

how are outliers defined?

Answer 20

they are 1.5 * IQR outside the IQR

Question 21

what are the percentages on a bell curve that represent μ + nσ.

Answer 21

68% for one σ
95% for 2σ
99.7% for 3σ

Question 22

What is the difference and similarity between quota and stratified sampling?

Answer 22

Quota sampling is opportunistic but samples are ignored if the quota they belong to is full.

They both have mutually exclusive groups that are filled based of the proportion of that group in the whole population.