The 95% confidence interval for the slope coefficient b is calculated using the formula:
CI=b^±t2α,n−2sb^
Where:
- b^=0.6 (point estimate)
- sb^=0.2 (standard error)
- α=5%, so α/2=0.025
- Degrees of freedom = n - 2 = 36 - 2 = 34
- t0.025,34=±2.03 (from t-distribution table)
Calculation:
CI=0.6±2.03×0.2=0.6±0.406=[0.194,1.006]
Therefore, the 95% confidence interval is $0.194 < b < 1.006$.
Note: The degrees of freedom are n-2 because we're estimating two parameters (intercept and slope) in simple linear regression.