A Symbols
A.1 General notes
Greek letters represent population parameter values; roman letters represent sample values.
A Greek letter with a "hat" represents and estimate of the population value from the sample; i.e., μx represents the true population mean of X, while ˆμx represents its estimate from the sample.
A.2 Table of symbols
symbol | pronunciation | definition |
---|---|---|
μ | meeYU | generally, a population mean; sometimes, a model intercept. μx represents the mean of x |
σ | sigma | lower case sigma is the standard deviation; σx is the standard deviation of X |
σ2 | sigma squared | variance |
ρ | row | population correlation; ρxy is the correlation in the population between X and Y |
r | row | sample correlation; r_{xy} is the correlation in the sample between X and Y |
Σ | sigma | the capital letter sigma in boldface represents a variance-covariance matrix |
∑ | sigma | upper case sigma is an instruction to add; e.g., ∑Xi is the instruction to sum together all values of X. |
β | beta | regression coefficient |
∼ | is distributed as | e.g., e∼N(μ,σ2) means that e is distributed as a Normal distribution with mean μ and variance σ2 |
γ | gamma | fixed effects, correlation coefficients in a mixed-effects regression |
τ | tau | by-subject variance component (random effects parameter) in a mixed-effects regression |
ω | omega | by-stimulus variance component (random effects parameter) in a mixed-effects regression |
S0s | S sub zero S | by-subject random intercept effect for subject s |
S1s | S sub one S | by-subject random slope effect for subject s |