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 is significant at the 5% level.
Given:
- Significance level = 5%
To check the significance of , we compare the calculated value of with the critical value of from a table (based on sample size and significance level). The sample size is 5 (since we have 5 data points).
Degrees of Freedom (df)
For and a significance level of 0.05, the critical value of is approximately 0.878.
Since the absolute value of , i.e., , is greater than the critical value of 0.878, is significant at the 5% level.
Step 2: Calculate the equation of the regression line.
The regression line equation is of the form: Where:
- is the slope
- is the y-intercept
Formula for slope :
Where:
- is the standard deviation of the hours jogged (y-values)
- is the standard deviation of the ages (x-values)
Formula for intercept :
Where and are the means of the x-values and y-values, respectively.
Now, let's calculate these values.
- (mean of ages) =
- (mean of hours jogged) =
Let's compute the slope and intercept .The calculations give us the following results:
- Mean of ages () = 44.4
- Mean of hours jogged () = 3.2
- Standard deviation of ages () = 16.3340
- Standard deviation of hours jogged () = 2.3076
- Slope () ≈ -0.1344
- Intercept () ≈ 9.1653
Equation of the regression line:
This is the equation of the regression line.
Since 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:
- What is the interpretation of the slope in this regression line?
- How would the regression line change if the correlation were closer to 0?
- Can we predict the number of hours jogged for someone aged 40 using this regression equation?
- How does the standard deviation of the data affect the slope of the regression line?
- 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.
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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)
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