Math Problem Statement

The following table gives the data for the average temperature and the snow accumulation in several small towns for a single month. Determine the equation of the regression line, yˆ=b0+b1x. Round the slope and y-intercept to the nearest thousandth. Then determine if the regression equation is appropriate for making predictions at the 0.01 level of significance.

Critical Values of the Pearson Correlation Coefficient

Average Temperatures and Snow AccumulationsAverage Temperature (℉)

39

34

19

41

44

22

25

20

25

42

Snow Accumulation (in.)

10

16

28

10

14

25

26

16

14

10

Solution

To solve this problem, we need to:

  1. Find the equation of the regression line y^=b0+b1x\hat{y} = b_0 + b_1x, where:

    • b1b_1 is the slope of the regression line.
    • b0b_0 is the y-intercept.
  2. Determine if the regression equation is appropriate for making predictions at the 0.01 level of significance, using the Pearson correlation coefficient rr and comparing it to critical values.

Step 1: Data summary

Here is the dataTo solve this problem, we need to:

  1. Find the equation of the regression line y^=b0+b1x\hat{y} = b_0 + b_1x, where:

    • b1b_1 is the slope of the regression line.
    • b0b_0 is the y-intercept.
  2. Determine if the regression equation is appropriate for making predictions at the 0.01 level of significance, using the Pearson correlation coefficient rr and comparing it to critical values.

Step 1: Data summary

Here is the

  • Average Temperature (x): [39,34,19,41,44,22,25,20,25,42][39, 34, 19, 41, 44, 22, 25, 20, 25, 42]
  • Snow Accumulation (y): [10,16,28,10,14,25,26,16,14,10][10, 16, 28, 10, 14, 25, 26, 16, 14, 10]

We will now calculate the slope b1b_1, the intercept b0b_0, and the correlation coefficient rr using statistical formulas for linear regression.

Step 2: Calculating the slope b1b_1 and intercept b0b_0

The formulas for linear regression coefficients are:

b1=n(xy)xynx2(x)2b_1 = \frac{n\sum(xy) - \sum x \sum y}{n \sum x^2 - (\sum x)^2} b0=yb1xnb_0 = \frac{\sum y - b_1 \sum x}{n}

Where:

  • xx = average temperature
  • yy = snow accumulation
  • nn = number of data points (here n=10n = 10)

I'll calculate this now.The equation of the regression line is:

y^=33.6310.538x\hat{y} = 33.631 - 0.538x

Step 3: Determine if the regression equation is appropriate for predictions at the 0.01 level of significance

To do this, we need to compute the Pearson correlation coefficient rr and compare it with the critical values for the significance level α=0.01\alpha = 0.01. The formula for rr is:

r=nxyxy(nx2(x)2)(ny2(y)2)r = \frac{n \sum xy - \sum x \sum y}{\sqrt{(n \sum x^2 - (\sum x)^2)(n \sum y^2 - (\sum y)^2)}}

We will now compute rr and check its significance.The Pearson correlation coefficient r=0.767r = -0.767.

Step 4: Checking significance at the 0.01 level

To determine if the regression equation is appropriate for making predictions, we compare the absolute value of rr with the critical value for the Pearson correlation coefficient at n2=8n - 2 = 8 degrees of freedom for α=0.01\alpha = 0.01. The critical value for α=0.01\alpha = 0.01 with 8 degrees of freedom is approximately 0.765.

Since r=0.767|r| = 0.767 is slightly greater than the critical value of 0.765, the correlation is statistically significant at the 0.01 level. Therefore, the regression equation is appropriate for making predictions at this level of significance.


Would you like to go over any specific details or calculations? Here are five related questions:

  1. How do you interpret the slope in the context of temperature and snow accumulation?
  2. What is the meaning of the correlation coefficient being negative?
  3. How would predictions differ if the correlation coefficient were weaker?
  4. Can the regression line be used for all temperature values, or are there limitations?
  5. How does the significance level affect the reliability of the regression model?

Tip: Always check the assumptions of regression, such as linearity and homoscedasticity, before making predictions.

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Math Problem Analysis

Mathematical Concepts

Linear Regression
Pearson Correlation
Statistical Significance

Formulas

Regression line formula: ŷ = b0 + b1x
Slope: b1 = (nΣxy - ΣxΣy) / (nΣx^2 - (Σx)^2)
Intercept: b0 = (Σy - b1Σx) / n
Pearson Correlation Coefficient: r = (nΣxy - ΣxΣy) / sqrt((nΣx^2 - (Σx)^2)(nΣy^2 - (Σy)^2))

Theorems

Critical Values for Pearson Correlation
Linear Regression Theory

Suitable Grade Level

Grade 12 or Early College