a) We can see from the table that with the increase in value of x , there is decrease in value of y , hence we can say that coefficient of correlation is negative b) Equation of least squares is y = − 2.9866 x + 24.92 and correlation coefficient r = − 0.9995 Plot is c) Predicted value of y at x = 2.4 is 17.752 Given information: Five points x −4 −3 −1 3 5 y 3.7 33.7 27.5 16.4 9.8 Formula used: Slope, m = ∑ i = 1 n ( x i − X ¯ ) ( y i − Y ¯ ) ∑ i = 1 n ( x i − X ¯ ) 2 Y axis intercept, b = Y ¯ − m X ¯ Correlation Coefficient, r = ∑ i = 1 n ( x i − X ¯ ) ( y i − Y ¯ ) ∑ i = 1 n ( x i − X ¯ ) 2 ∑ i = 1 n ( y i − Y ¯ ) 2 Where x i and y i are the i th entry of x and y ; X ¯ and Y ¯ are means of x and y Calculation: Step 1: Calculate the mean of x and y X ¯ = ( − 4 ) + ( − 3 ) + ( − 1 ) + 3 + 5 5 = 0 Y ¯ = 37.2 + 33.7 + 27.5 + 16.4 + 9.8 5 = 24.92 Step 2: Plot the table as shown i x i y i x i − X ¯ y i − Y ¯ ( x i − X ¯ ) 2 ( x i − X ¯ ) ( y i − Y ¯ ) ( y i − Y ¯ ) 2 1 -4 37.2 -4 12.28 16 -49.12 150.7984 2 -3 33.7 -3 8.78 9 -26.34 77.0884 3 -1 27.5 -1 2.58 1 -2.58 6.6564 4 3 16.4 3 -8.52 9 -25.56 72.5904 5 5 9.8 5 -15.12 25 -75.6 228.6144 ∑ i = 1 n ( x i − X ¯ ) 2 = 60 ∑ i = 1 n ( x i − X ¯ ) ( y i − Y ¯ ) = − 179.2 ∑ i = 1 n ( y i − Y ¯ ) 2 = 535.7480 Step 3: Calculate the slope m = ∑ i = 1 n ( x i − X ¯ ) ( y i − Y ¯ ) ∑ i = 1 n ( x i − X ¯ ) 2 = − 179.2 60 ≈ − 2.9866 Step 4: Calculate y intercept b = Y ¯ − m X ¯ = 24.92 − ( − 2.9866 × 0 ) ≈ 24.92 The slope of the line is − 2.9866 and y intercept is 24.92 Using slope intercept form, y = m x + b ,equation is y = − 2.9866 x + 24.92 ; Step 5: Draw the scatter plot Step 6: Calculate the Correlation coefficient r = ∑ i = 1 n ( x i − X ¯ ) ( y i − Y ¯ ) ∑ i = 1 n ( x i − X ¯ ) 2 ∑ i = 1 n ( y i − Y ¯ ) 2 = − 179.2 60 × 535.7480 ≈ − 0.9995 Step 7: Prediction for x = 2.4 ; plug x = 2.4 in y = − 2.9866 x + 24.92 y = − 2.9866 ( 2.4 ) + 24.92 = 17.752
a) We can see from the table that with the increase in value of x , there is decrease in value of y , hence we can say that coefficient of correlation is negative b) Equation of least squares is y = − 2.9866 x + 24.92 and correlation coefficient r = − 0.9995 Plot is c) Predicted value of y at x = 2.4 is 17.752 Given information: Five points x −4 −3 −1 3 5 y 3.7 33.7 27.5 16.4 9.8 Formula used: Slope, m = ∑ i = 1 n ( x i − X ¯ ) ( y i − Y ¯ ) ∑ i = 1 n ( x i − X ¯ ) 2 Y axis intercept, b = Y ¯ − m X ¯ Correlation Coefficient, r = ∑ i = 1 n ( x i − X ¯ ) ( y i − Y ¯ ) ∑ i = 1 n ( x i − X ¯ ) 2 ∑ i = 1 n ( y i − Y ¯ ) 2 Where x i and y i are the i th entry of x and y ; X ¯ and Y ¯ are means of x and y Calculation: Step 1: Calculate the mean of x and y X ¯ = ( − 4 ) + ( − 3 ) + ( − 1 ) + 3 + 5 5 = 0 Y ¯ = 37.2 + 33.7 + 27.5 + 16.4 + 9.8 5 = 24.92 Step 2: Plot the table as shown i x i y i x i − X ¯ y i − Y ¯ ( x i − X ¯ ) 2 ( x i − X ¯ ) ( y i − Y ¯ ) ( y i − Y ¯ ) 2 1 -4 37.2 -4 12.28 16 -49.12 150.7984 2 -3 33.7 -3 8.78 9 -26.34 77.0884 3 -1 27.5 -1 2.58 1 -2.58 6.6564 4 3 16.4 3 -8.52 9 -25.56 72.5904 5 5 9.8 5 -15.12 25 -75.6 228.6144 ∑ i = 1 n ( x i − X ¯ ) 2 = 60 ∑ i = 1 n ( x i − X ¯ ) ( y i − Y ¯ ) = − 179.2 ∑ i = 1 n ( y i − Y ¯ ) 2 = 535.7480 Step 3: Calculate the slope m = ∑ i = 1 n ( x i − X ¯ ) ( y i − Y ¯ ) ∑ i = 1 n ( x i − X ¯ ) 2 = − 179.2 60 ≈ − 2.9866 Step 4: Calculate y intercept b = Y ¯ − m X ¯ = 24.92 − ( − 2.9866 × 0 ) ≈ 24.92 The slope of the line is − 2.9866 and y intercept is 24.92 Using slope intercept form, y = m x + b ,equation is y = − 2.9866 x + 24.92 ; Step 5: Draw the scatter plot Step 6: Calculate the Correlation coefficient r = ∑ i = 1 n ( x i − X ¯ ) ( y i − Y ¯ ) ∑ i = 1 n ( x i − X ¯ ) 2 ∑ i = 1 n ( y i − Y ¯ ) 2 = − 179.2 60 × 535.7480 ≈ − 0.9995 Step 7: Prediction for x = 2.4 ; plug x = 2.4 in y = − 2.9866 x + 24.92 y = − 2.9866 ( 2.4 ) + 24.92 = 17.752
Definition Definition Statistical measure used to assess the strength and direction of relationships between two variables. Correlation coefficients range between -1 and 1. A coefficient value of 0 indicates that there is no relationship between the variables, whereas a -1 or 1 indicates that there is a perfect negative or positive correlation.
Chapter 2.1, Problem 104E
To determine
To determine:
a) We can see from the table that with the increase in value of x
, there is decrease in value of y
, hence we can say that coefficient of correlation is negative
b) Equation of least squares is y=−2.9866x+24.92
and correlation coefficientr=−0.9995
Plot is
c) Predicted value of y at x=2.4
is 17.752
Given information: Five points
x
−4
−3
−1
3
5
y
3.7
33.7
27.5
16.4
9.8
Formula used: Slope, m=∑i=1n(xi−X¯)(yi−Y¯)∑i=1n(xi−X¯)2
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, algebra and related others by exploring similar questions and additional content below.
Correlation Vs Regression: Difference Between them with definition & Comparison Chart; Author: Key Differences;https://www.youtube.com/watch?v=Ou2QGSJVd0U;License: Standard YouTube License, CC-BY
Correlation and Regression: Concepts with Illustrative examples; Author: LEARN & APPLY : Lean and Six Sigma;https://www.youtube.com/watch?v=xTpHD5WLuoA;License: Standard YouTube License, CC-BY