Download business statistics cheat sheet and more Cheat Sheet Business Statistics in PDF only on Docsity! Econ 205 - Cheat Sheet Statistics for Business and Economics Descriptive statistics: Mean: x̄ =average(DATA), Median =median(DATA) , Mode =mode(DATA) Variance: σ2 = var.p (DATA) , s2 = var.s (DATA) , s2 = σ2 ( N n−1 ) or σ2 = s2 ( n−1 N ) Standard deviation: s = √∑n i=1(xi−x̄)2 n−1 = stdev.s(DATA) = σ √ N n−1 σ = √∑N i=1(xi−µ)2 N = stdev.p(DATA)= s √ n−1 N Coefficient of variation: CV = sx̄ or CV = σ µ Pth-percentile =percentile.exc(data,P/100) or location formula LP = (n+ 1) P 100 Covariance: σXY =covariance.s(data) or Data-Analysis-Toolpak Covariance , σXY = sXY n−1 N Correlation coefficient: ρXY = correl(data) or Data-Analysis-Toolpak Correlation Regression model: y = β0 + β1x+ ε Regression line estimated: ŷ = b0 + b1x in Scatterplot Add Trendline or Data-Analysis-Toolpak Regression Probability: Rule of complements: P (Ac) = 1− P (A) Multiplication formulat: P (A and B) = P (A|B)× P (B) Addition formulat: P (A or B) = P (A) + P (B)− P (A and B) Conditional probability: P (A|B) = P (A and B)P (B) = P (A|B)×P (B) P (B) Independence: A and B are independent if P (A and B) = P (A)× P (B) or when P (A|B) = P (A) Mean (aka expected value) of a discrete distribution: µ = ∑n i=1 xiP (xi) E [c] = c, V ar [c] = 0; E [X + c] = E [X] + c, V ar [X + c] = V ar [X] ; E [cX] = cE [X] , V ar [cX] = c2V ar [X] Distributions: • Binomial distribution: P (X = x) = binom.dist (x, n, π, 0) and P (X ≤ x) = binom.dist (x, n, π, 1) • Mean of binomial distribution: µ = E [X] = n× π and σ2 = V ar [X] = n× π × (1− π) • Uniform distribution: X ∼ U [a, b] , then density is f = 1b−a and E [X] = a+b 2 and V [X] = 1 12 (b− a) 2 • Normal distribution: X ∼ N (µ, σ) : P (X < x) = P ( X−µ σ < x−µ σ ) where Z = X−µσ ∼ N (0, 1) then: to-the-left : P (Z < z) = norm.s.dist (z) , or to-the-right : P (Z > z) = 1− norm.s.dist (z) , and the πth percentile Pπ = norm.s.inv (π)
