STATISTICAL SYMBOLS

MT 21 LEC

X

A single element

N

Number of elements in a population

n

Number of elements in a sample

p

The probability of an event occurring. In reports of statistical significance, p is the probability that the result could have been obtained by chance, i.e., the probability that a type I error is being made

q

The probability of an event not occurring; equal to (1 − p)

f

Frequency

C

Centile (or percentile) rank; or confidence level

Mo

Mode

Mdn

Median

μ

Population mean

x̄

Sample mean

∑

The sum of

x

Deviation score

σ²

Population variance

S²

Sample variance

σ

Population standard deviation (SD)

S

Sample standard deviation (SD)

z

The number of standard deviations by which a single element in a normally distributed population lies from the population mean; or the number of standard errors by which a random sample mean lies from the population mean

μₓ̄

The mean of the random sampling distribution of means

σₓ̄

Standard error or standard error of the mean (standard deviation of the random sampling distribution of means) [SEM or SE]

Sₓ̄

Estimated standard error (estimated standard error of the mean)

t

The number of estimated standard errors by which a random sample mean lies from the population mean

df

Degrees of freedom

α

The criterion level at which the null hypothesis will be accepted or rejected; the probability of making a type I error

β

Probability of making a type II error

χ²

Chi-square; a test of proportions

r

Correlation coefficient

ρ

Rho; Spearman rank order correlation coefficient

r²

Coefficient of determination

b

Regression coefficient; the slope of the regression line