Create Day-8_PearsonCorrelationCoefficient-II.txt

Day-8/Day-8_PearsonCorrelationCoefficient-II.txt

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+# Step 1, Rewrite the 2 lines in proper form
+
+Rewrite the 2 lines as:
+
+y = -2 + (-3/4) * x
+x = -7/4 + (-3/4) * y
+
+so b1 = -3/4 and b2 = -3/4
+
+# Step 2, Apply Pearson's Coefficient formula
+
+Let p = pearson coefficient
+Let x_std = standard deviation of x
+Let y_std = standard deviation of y
+
+From the tutorial we have:
+
+p = b1 (x_std / y_std)
+p = b2 (y_std / x_std)
+
+Multiplying these 2 equations together we get
+p^2 = b1 * b2
+p^2 = (-3/4) * (-3/4)
+p^2 = 9/16
+p = 3/4 or -3/4 (depending on correlation of x and y)
+
+# Step 3, Find out if p is postive or negative
+
+Notice that both of the original line equations have negative slopes, so x and y are negatively correlated by definition.
+So, p = -3/4