Confidence Interval on Difference Between Means, Independent Groups, Standard Deviation Estimated (3 of 7)

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A t table shows that the value of t for a 99% confidence interval for 6 df is 3.707. The only remaining term is .

The first step is to compute and :

= 0.917 and = 0.667.

MSE = (0.917 + 0.667)/2 = .792.

From the formula:





= 0.629

All the terms needed to construct the confidence interval have now been computed. The lower limit (LL) of the interval is:

LL = M_d - t

= -2.25 - (3.707)(0.629)
= -4.58.

UL = -2.25 + (3.707)(0.629) = 0.09.
Therefore -4.58 ≤ μ₁ - μ₂ ≤ 0.09.