STAT Symbols and Formulae Flashcards

Memorize common statistics symbols and formulae for GMU class STAT-250

1
Q

μ
(mu)

A

μ is population mean

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2
Q

μ (mu) should only be used with

A

symmetric data

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3
Q

N

A

population size

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4
Q

n

A

sample size

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5
Q

p

A

population proportion

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6
Q


(p-hat)

A

sample proportion

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7
Q

median is not used for

A

population

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8
Q

m

A

median

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9
Q

m is appropriate for

A

median is appropriate for symmetric data

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10
Q


(x-bar)

A

sample mean

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11
Q

x̄ (x-bar) can only be used with

A

symmetric data

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12
Q

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

A

sample difference of proportions

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13
Q

p1-p2
(p sub1 minus p sub2)

A

population difference of proportions

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14
Q

σ

(lower case sigma)

A

population standard deviation

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15
Q

s

A

sample standard deviation

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16
Q

The 95% rule states that if _________, then ________

A

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

17
Q

z-score tells____

A

how many standard deviations a given value is from the mean

18
Q

population z-score formula

A

z = x - μ / σ

19
Q

sample z-score formula

A

z = x - x̄ / s

20
Q

z-score is most often between

21
Q

IQR meaning and formula

A

Interquartile range is Q3-Q1

22
Q

Fence rule

A

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

23
Q

SE

A

Standard error

24
Q

The standard error compares

A

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

25
The 95% rule for sampling distribution
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
26
Increasing sample size will
decrease standard error
27
Normal distributions (N) are:
bell-shaped and symmetric
28
How to compare one categorical and one quantitative variable?
Difference in means
29
μ1 - μ2
difference in population means
30
1 - x̄2
difference in sample means
31
Ha: (H sub-a)
Alternative hypothesis
32
H0: (H sub-zero)
the Null hypothesis
33
What is the difference between margin of error and standard deviation / standard error?
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.
34
α
Significance level Greek letter lowercase alpha
35
P < 0.05 means? (not a parameter)
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.
36
"If p-value is low....
reject H-O" (H0, the null hypothesis)
37
If p-value is high (higher than α),
do NOT reject the null hypothesis H0