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# Elementary Statistics: Symbols and their Meanings

Summary: Note: This module is currently under revision, and its content is subject to change. This module is being prepared as part of a statistics textbook that will be available for the Fall 2008 semester.

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Table 1: Symbols and their Meanings
Chapter (1st used) Symbol Spoken Meaning

1 The square root of same
1 ππ Pi 3.14159… (a specific number)
2 Q1Q1 Quartile one the first quartile
2 Q2Q2 Quartile two the second quartile
2 Q3Q3 Quartile three the third quartile
2 IQRIQR inter-quartile range Q3-Q1 = IQR
2 x ¯ x ¯ x-bar sample mean
2 μμ mu population mean
2 s sx sx s sample standard deviation
2 s2 s2x s-sqaured sample variance
2 σ σx σx sigma population standard deviation
2 σ2 σ2x sigma-squared population variance
2 ΣΣ capital sigma sum
3 { } {} brackets set notation
3 SS S sample space
3 AA Event A event A
3 P ( A ) P ( A ) probability of A probability of A occurring
3 P ( A B ) P ( A B ) probability of A given B prob. of A occurring given B has occurred
3 P ( A or B ) P ( A or B ) prob. of A or B prob. of A or B or both occurring
3 P ( A and B ) P ( A and B ) prob. of A and B prob. of both A and B occurring (same time)
3 A'A' A-prime, complement of A complement of A, not A
3 P ( A' ) P ( A' ) prob. of complement of A same
3 G 1 G 1 green on first pick same
3 P ( G 1 ) P ( G 1 ) prob. of green on first pick same
4 PDFPDF prob. distribution function same
4 XX X the random variable X
4 X~X~ the distribution of X same
4 BB binomial distribution same
4 GG geometric distribution same
4 HHH hypergeometric dist. same
4 PP Poisson dist. same
4 λλ Lambda average of Poisson distribution
4 greater than or equal to same
4 less than or equal to same
4 == equal to same
4 not equal to same
5 f ( x ) f ( x ) f of x function of x
5 pdfpdf prob. density function same
5 UU uniform distribution same
5 ExpExp exponential distribution same
5 xx k critical value
5 f ( x ) = f ( x ) = f of x equals same
5 mm m decay rate (for exp. dist.)
6 N N size 12{N} {} normal distribution same
6 z z size 12{z} {} z-score same
6 Z Z size 12{Z} {} standard normal dist. same
7 CLT CLT size 12{ ital "CLT"} {} Central Limit Theorem same
7 X¯ X X-bar the random variable X-bar
7 μ x μ x size 12{μ rSub { size 8{x} } } {} mean of X the average of X
7 μ x ¯ μ x ¯ size 12{μ rSub { size 8{ {overline {x}} } } } {} mean of X-bar the average of X-bar
7 σ x σ x size 12{σ rSub { size 8{x} } } {} standard deviation of X same
7 σ x ¯ σ x ¯ size 12{σ rSub { size 8{ {overline {x}} } } } {} standard deviation of X-bar same
7 ΣXΣX sum of X same
7 ΣxΣx sum of x same
8 CL CL size 12{ ital "CL"} {} confidence level same
8 CI CI size 12{ ital "CI"} {} confidence interval same
8 EBM EBM size 12{ ital "EBM"} {} error bound for a mean same
8 EBP EBP size 12{ ital "EBP"} {} error bound for a proportion same
8 t t size 12{t} {} student-t distribution same
8 df df size 12{ ital "df"} {} degrees of freedom same
8 t α 2 t α 2 student-t with a/2 area in right tail same
8 p' p p-hat sample proportion of success
8 P' P distribution of p-hat dist. of sample proportions
8 q' q q-hat sample proportion of failure
9 H 0 H 0 size 12{H rSub { size 8{0} } } {} H-naught, H-sub 0 null hypothesis
9 H a H a size 12{H rSub { size 8{a} } } {} H-a, H-sub a alternate hypothesis
9 H 1 H 1 size 12{H rSub { size 8{1} } } {} H-1, H-sub 1 alternate hypothesis
9 α α size 12{α} {} alpha probability of Type I error
9 β β size 12{β} {} beta probability of Type II error
10 X1 ¯ X2 ¯ X1 ¯ X2 ¯ size 12{ {overline {X1}} - {overline {X2}} } {} X1-bar minus X2-bar difference in sample means
μ 1 μ 2 μ 1 μ 2 size 12{μ rSub { size 8{1} } - μ rSub { size 8{2} } } {} mu-1 minus mu-2 difference in population means
P ' 1 P ' 2 P ' 1 P ' 2 size 12{P' rSub { size 8{1} } - P' rSub { size 8{2} } } {} P1-hat minus P2-hat difference in sample proportions
p 1 p 2 p 1 p 2 size 12{p rSub { size 8{1} } - p rSub { size 8{2} } } {} p1 minus p2 difference in population proportions
11 Χ 2 Χ 2 Ky-square Chi-square
OO Observed Observed frequency
EE Expected Expected frequency
12 y = a + bx y=a+bx y equals a plus b-x equation of a line
ŷŷ y-hat estimated value of y
rr correlation coefficient same
εε error same
SSESSE Sum of Squared Errors same
1.9 s 1.9s 1.9 times s cut-off value for outliers
13 FF F ratio F ratio

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