Math Problem Statement

A researcher hopes to determine whether the number of hours a person jogs per week is related to the person's age.

Age, 

x

Hours, 

y

34

3.5

22

7

48

2.5

56

2

62

1

r

r=

-0.951

Find the equation of the regression line and draw the line on the scatter plot, but only if r is significant. Round the slope and y-intercept to four decimal places, if necessary.

r▼(Choose one) significant at the 5% level. The equation of the regression line is 

y=− x.

Solution

To solve this, we'll go step by step:

Step 1: Check if the correlation coefficient rr is significant at the 5% level.

Given:

  • r0.951r \approx -0.951
  • Significance level = 5%

To check the significance of rr, we compare the calculated value of rr with the critical value of rr from a table (based on sample size and significance level). The sample size nn is 5 (since we have 5 data points).

Degrees of Freedom (df)

df=n2=52=3\text{df} = n - 2 = 5 - 2 = 3

For df=3df = 3 and a significance level of 0.05, the critical value of rr is approximately 0.878.

Since the absolute value of rr, i.e., r=0.951|r| = 0.951, is greater than the critical value of 0.878, rr is significant at the 5% level.

Step 2: Calculate the equation of the regression line.

The regression line equation is of the form: y=b1x+b0y = b_1 x + b_0 Where:

  • b1b_1 is the slope
  • b0b_0 is the y-intercept

Formula for slope b1b_1:

b1=r(sysx)b_1 = r \left( \frac{s_y}{s_x} \right) Where:

  • sys_y is the standard deviation of the hours jogged (y-values)
  • sxs_x is the standard deviation of the ages (x-values)

Formula for intercept b0b_0:

b0=yˉb1xˉb_0 = \bar{y} - b_1 \bar{x} Where xˉ\bar{x} and yˉ\bar{y} are the means of the x-values and y-values, respectively.

Now, let's calculate these values.

  • xˉ\bar{x} (mean of ages) = 34+22+48+56+625\frac{34 + 22 + 48 + 56 + 62}{5}
  • yˉ\bar{y} (mean of hours jogged) = 3.5+7+2.5+2+15\frac{3.5 + 7 + 2.5 + 2 + 1}{5}

Let's compute the slope b1b_1 and intercept b0b_0.The calculations give us the following results:

  • Mean of ages (xˉ\bar{x}) = 44.4
  • Mean of hours jogged (yˉ\bar{y}) = 3.2
  • Standard deviation of ages (sxs_x) = 16.3340
  • Standard deviation of hours jogged (sys_y) = 2.3076
  • Slope (b1b_1) ≈ -0.1344
  • Intercept (b0b_0) ≈ 9.1653

Equation of the regression line:

y=0.1344x+9.1653y = -0.1344x + 9.1653

This is the equation of the regression line.

Since rr is significant, we can proceed to plot the scatter plot and regression line.

Would you like me to plot the regression line along with the scatter plot? If yes, I can generate that for you.


Here are 5 related questions to expand the discussion:

  1. What is the interpretation of the slope in this regression line?
  2. How would the regression line change if the correlation were closer to 0?
  3. Can we predict the number of hours jogged for someone aged 40 using this regression equation?
  4. How does the standard deviation of the data affect the slope of the regression line?
  5. What would the effect of removing an outlier (like a 22-year-old jogging 7 hours) have on the line?

Tip:

Always check the significance of the correlation coefficient before interpreting a regression line.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Statistics
Linear Regression
Correlation Coefficient

Formulas

Slope formula: b1 = r * (sy / sx)
Intercept formula: b0 = ȳ - b1 * x̄
Regression line equation: y = b1x + b0

Theorems

Significance testing for correlation coefficients

Suitable Grade Level

College level (Introductory Statistics)