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STATISTICS II
ABBREVIATIONS CHEAT SHEET
KOEN HANEGREEFS
VUB
, Statistics II — Abbreviations & Symbols
1. Greek letters — population parameters (usually unknown)
Symbol Meaning
μ (mu) Population mean
σ (sigma) Population standard deviation
σ² Population variance
p Population proportion (probability of success)
q=1−p Population proportion of failures
π (pi) Sometimes used for population proportion; in this course textbook always p
α (alpha) Significance level — probability of a Type I error (e.g. 0.05)
β (beta) Probability of a Type II error; 1 − β = power of the test
β₀, β₁ True (population) regression intercept and slope
ρ (rho) Population correlation coefficient
χ² (chi-squared) Chi-square test statistic / distribution
ε (epsilon) Random error term in the regression model y = β₀ + β₁x + ε
Δ (delta) Difference, e.g. Δ = μ₁ − μ₂
Σ (capital sigma) Summation operator: Σxᵢ means add all the xᵢ
ν (nu) Sometimes used for degrees of freedom in tables
2. Roman letters — sample statistics (computed from data)
Symbol Meaning
n Sample size of a single group
n₁, n₂ Sample sizes for group 1 and group 2
N Population size
ȳ (y-bar) or x̄ Sample mean
s Sample standard deviation
s² Sample variance
p̂ (p-hat) Sample proportion of successes
q̂ = 1 − p̂ Sample proportion of failures
b₀, b₁ Estimated regression intercept and slope (from sample data)
ŷ (y-hat) Predicted / fitted value from a regression model
e=y−ŷ Residual = observed value minus predicted value
r Sample correlation coefficient, −1 ≤ r ≤ 1
Coefficient of determination — proportion of variability in y explained by the
R²
model
sₑ (or s) Standard deviation of the residuals — in R: 'Residual standard error'
z Standardised score: z = (x − μ) / σ; also Normal-based test statistic
t t-statistic, used when σ is unknown
F F-statistic: ratio of two variances (ANOVA, regression overall test)
W Wilcoxon signed-rank test statistic (non-parametric)
U Mann–Whitney U statistic (non-parametric, two independent samples)
H Kruskal–Wallis test statistic (non-parametric ANOVA)
Page
STATISTICS II
ABBREVIATIONS CHEAT SHEET
KOEN HANEGREEFS
VUB
, Statistics II — Abbreviations & Symbols
1. Greek letters — population parameters (usually unknown)
Symbol Meaning
μ (mu) Population mean
σ (sigma) Population standard deviation
σ² Population variance
p Population proportion (probability of success)
q=1−p Population proportion of failures
π (pi) Sometimes used for population proportion; in this course textbook always p
α (alpha) Significance level — probability of a Type I error (e.g. 0.05)
β (beta) Probability of a Type II error; 1 − β = power of the test
β₀, β₁ True (population) regression intercept and slope
ρ (rho) Population correlation coefficient
χ² (chi-squared) Chi-square test statistic / distribution
ε (epsilon) Random error term in the regression model y = β₀ + β₁x + ε
Δ (delta) Difference, e.g. Δ = μ₁ − μ₂
Σ (capital sigma) Summation operator: Σxᵢ means add all the xᵢ
ν (nu) Sometimes used for degrees of freedom in tables
2. Roman letters — sample statistics (computed from data)
Symbol Meaning
n Sample size of a single group
n₁, n₂ Sample sizes for group 1 and group 2
N Population size
ȳ (y-bar) or x̄ Sample mean
s Sample standard deviation
s² Sample variance
p̂ (p-hat) Sample proportion of successes
q̂ = 1 − p̂ Sample proportion of failures
b₀, b₁ Estimated regression intercept and slope (from sample data)
ŷ (y-hat) Predicted / fitted value from a regression model
e=y−ŷ Residual = observed value minus predicted value
r Sample correlation coefficient, −1 ≤ r ≤ 1
Coefficient of determination — proportion of variability in y explained by the
R²
model
sₑ (or s) Standard deviation of the residuals — in R: 'Residual standard error'
z Standardised score: z = (x − μ) / σ; also Normal-based test statistic
t t-statistic, used when σ is unknown
F F-statistic: ratio of two variances (ANOVA, regression overall test)
W Wilcoxon signed-rank test statistic (non-parametric)
U Mann–Whitney U statistic (non-parametric, two independent samples)
H Kruskal–Wallis test statistic (non-parametric ANOVA)
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