1. 皮爾遜相關係數 (Pearson Correlation Coefficient):
1.1 衡量兩個值線性相關強度的量
1.2 取值範圍 [-1, 1]:
正向相關: >0, 負向相關:<0, 無相關性:=0
2. R平方值:
2.1定義:決定係數,反應因變量的全部變異能通過迴歸關係被自變量解釋的比例。
2.2 描述:如R平方爲0.8,則表示迴歸關係可以解釋因變量80%的變異。換句話說,如果我們能控制自變量不變,則因變量的變異程度會減少80%
2.3: 簡單線性迴歸:R^2 = r * r
多元線性迴歸:
Python實現;
import numpy as np
from astropy.units import Ybarn
import math
def computeCorrelation(X, Y):
xBar = np.mean(X)
yBar = np.mean(Y)
SSR = 0
varX = 0
varY = 0
for i in range(0 , len(X)):
diffXXBar = X[i] - xBar
diffYYBar = Y[i] - yBar
SSR += (diffXXBar * diffYYBar)
varX += diffXXBar**2
varY += diffYYBar**2
SST = math.sqrt(varX * varY)
return SSR / SST
testX = [1, 3, 8, 7, 9]
testY = [10, 12, 24, 21, 34]
print (computeCorrelation(testX, testY))