Symbol formats

The table below summarizes the correct format of statistical parameters. In many cases, Greek letters are used to indicate the population parameter for a statistic, and corresponding English letters are used to indicate the sample statistic that is an estimate of that population parameter. Symbols should be italicized in all cases where they represent a constant value. Associated subscripts and superscripts are generally not italicized (but see below):

Population Parameter / Population Parameter Symbol / Sample Parameter / Sample Parameter Symbol
population size / N / sample size / n
population mean (arithmetic) / m (m in Symbol font) / sample mean (arithmetic) / (created using the Insert menu  Object…  Microsoft Equation function in Microsoft Office). The word “mean”, as in “mean = 27.2 is also acceptable.
population mean (geometric) / mG (mG in Symbol font) / sample mean (geometric) / (created using the Insert menu  Object…  Microsoft Equation function in Microsoft Office). The abbreviation “GM”, as in “GM = 27.2 is also acceptable.
population mean (harmonic) / mH (mH in Symbol font) / sample mean (harmonic) / (created using the Insert menu Object…  Microsoft Equation function in Microsoft Office) The phrase “harmonic mean”, as in “harmonic mean = 27.2 is also acceptable.
population median / (“m-tilde” created using the Insert menu  Object…  Microsoft Equation function in Microsoft Office) / sample median / (“x-tilde”created using the Insert menu  Object…  Microsoft Equation function in Microsoft Office). The word “median”, as in “median = 27.2 is also acceptable.
population variance
population standard deviation / s2 (s2 in Symbol font)
s (s in Symbol font) / sample variance
sample standard deviation
standard error of the mean
coefficient of variation / s2
s
SE or SEM
CV
population skewness
population kurtosis / g1 (g1 in Symbol font)
g2 (g2 in Symbol font) / sample skewness
sample kurtosis / g1
g2
population correlation coefficient (Pearson’s)
coefficient of determination (population) / r (r in Symbol font)
r2 (r2 in Symbol font) / sample correlation coefficient (Pearson’s)
coefficient of determination (sample) / r
r2
regression line intercept / b0 (b0 in Symbol font) / Regression line intercept (estimated from sample data) / b0
regression line slope(s) / bi (bi in Symbol font, where i = the variable number) / Regression line slope(s) estimates from sample data) / bi (where i = the variable number)
regression line variables: y and x(s) / Your call: can be upper or lowercase, italicized or not.

Symbols used in statistical tests:

Probability should be expressed as P, and “alpha” as a (a in Symbol font).

Critical values are generally not reported.

There should always be a space on either side of any “equals sign” ( = ).

The test statistics z, t, chi-squared, and F should be represented as:

za (or za/2) neither subscript is italicized, but the numerical value for a or a/2 is substituted for the a (or a/2). Often (n = the sample size) is also included. The P-value may or may not be reported

ta (or ta/2) neither subscript is italicized, but the numerical value for a or a/2 is substituted. Always report the P value and the degrees of freedom or include the alpha and degrees of freedom in the subscript (e.g., t0.975,35 = the test statistic). Alternatively, report t = the test statistic (df, the degrees of freedom; P = the P-value).

c2 needs to have the alpha and degrees of freedom reported, as well as the P-value: c2a,df = the test statistic (e.g., c20.05,12). Alternatively, report c2 = the test statistic (df, the degrees of freedom; P = the P-value).

For F, always report both the numerator and the denominator degrees of freedom (e.g., F2,35 = the test statistic; P = the P-value) or include it in parentheses, e.g., (F(2,35) = the test statistic; P = the P-value).

Other symbols of potential value:

> greater than

≥ greater than or equal to (option >)

> much greater than

< less than

≤ less than or equal to (option <)

< much less than

= equal to

≠ (option =) not equal to

≈ (option-x) “approximately equal to”

´ (Symbol font) or • (option-8) multiplication sign

÷ (option-/) division sign

– (option--) subtraction sign (“m-dash”, wider than – “n-dash”)

∞ (option-5) infinity symbol (¥, the infinity symbol in Symbol font, is more often used)

° (option-shift-8) degree symbol

‰ (option-shift-R) “parts per thousand” symbol