STAT Symbols and Formulae

Question 1

μ
(mu)

Answer 1

μ is population mean

Question 2

μ (mu) should only be used with

Answer 2

symmetric data

Question 3

N

Answer 3

population size

Question 4

n

Answer 4

sample size

Question 5

p

Answer 5

population proportion

Question 6

p̂
(p-hat)

Answer 6

sample proportion

Question 7

median is not used for

Answer 7

population

Question 8

m

Answer 8

median

Question 9

m is appropriate for

Answer 9

median is appropriate for symmetric data

Question 10

x̄
(x-bar)

Answer 10

sample mean

Question 11

x̄ (x-bar) can only be used with

Answer 11

symmetric data

Question 12

p̂₁ - p̂₂
(p-hat sub1 minus p-hat sub 2)

Answer 12

sample difference of proportions

Question 13

p₁-p₂
(p sub1 minus p sub2)

Answer 13

population difference of proportions

Question 14

σ

(lower case sigma)

Answer 14

population standard deviation

Question 15

s

Answer 15

sample standard deviation

Question 16

The 95% rule states that if _________, then ________

Answer 16

If distribution is symmetric and bell-shaped, then ~95% should fall between x̄ - 2s to x̄ + 2s

Question 17

z-score tells____

Answer 17

how many standard deviations a given value is from the mean

Question 18

population z-score formula

Answer 18

z = x - μ / σ

Question 19

sample z-score formula

Answer 19

z = x - x̄ / s

Question 20

z-score is most often between

Answer 20

-3 to 3

Question 21

IQR meaning and formula

Answer 21

Interquartile range is Q3-Q1

Question 22

Fence rule

Answer 22

Upper fence is Q3 + 1.5(IQR)
Lower fence is Q1 - 1.5(IQR)

Question 23

SE

Answer 23

Standard error

Question 24

The standard error compares

Answer 24

Standard error compares typical distance that a sample is from the center - rather than an individual observation as in std deviation.

Question 25

The 95% rule for sampling distribution

Answer 25

95% of the data will fall between
statistic +/-2 (SE).
There is roughly a 95% chance that p̂ is no more than 2 standard deviations from p

Question 26

Increasing sample size will

Answer 26

decrease standard error

Question 27

Normal distributions (N) are:

Answer 27

bell-shaped and symmetric

Question 28

How to compare one categorical and one quantitative variable?

Answer 28

Difference in means

Question 29

μ₁ - μ₂

Answer 29

difference in population means

Question 30

x̄₁ - x̄₂

Answer 30

difference in sample means

Question 31

H_a:
(H sub-a)

Answer 31

Alternative hypothesis

Question 32

H₀:
(H sub-zero)

Answer 32

the Null hypothesis

Question 33

What is the difference between margin of error and standard deviation / standard error?

Answer 33

The margin of error is the total added and subtracted from the center to establish the interval.
MoE usually uses the standard error or standard deviation. For example, in a 95% CI based on the rule, Margin of Error = SE * 2. The total interval range will be SE * 4 or MoE * 2.

Question 34

α

Answer 34

Significance level
Greek letter lowercase alpha

Question 35

P < 0.05 means?
(not a parameter)

Answer 35

short hand notation such as P < 0.05 is used to indicate that the p-value is less than 0.05, which means the results are significant at a 5% level.

Question 36

“If p-value is low….

Answer 36

reject H-O”
(H₀, the null hypothesis)

Question 37

If p-value is high (higher than α),

Answer 37

do NOT reject the null hypothesis H₀