Question

A sample of 20 paired observations generates the following data: d−d− = 1.3 and s2DsD2 = 2.6. Assume a normal distribution. Use Table 2.

a.	Construct a 90% confidence interval for the mean difference μD. (Round intermediate calculations to 4 decimal places and final answers to 2 decimal places.)

  Confidence interval is  to .

b.

Using the confidence interval, test whether the mean difference differs from zero.

	The mean difference does not differ from zero.
	The mean difference differs from zero.

Answer 1

a)

sample mean 'x̄=	1.300
sample size   n=	20.00
sample std deviation s=	1.612

std error 'sx=s/√n=

0.361

for 90% CI; and 19 df, value of t=		1.729
margin of error E=t*std error    =		0.623
lower bound=sample mean-E =		0.68
Upper bound=sample mean+E =		1.923
from above 90% confidence interval for population mean =(0.68 to 1.92)

b)

since interval values are above 0 ,  The mean difference differs from zero.