ci_twosample_tpooled(A, B, cl)

Computes a confidence interval for the difference of two means (pooled test). Arrays A and B store the samples and cl is the confidence level.
Assumes samples are independent, populations are either normal or large, and the populations have the same standard deviation.


See also ci_twosample_pro ci_twosample_tnonpooled ci_twosample_tpaired 


Example


(See NOTE below)

a=(34.2, 90, 100.4, 24.6, 107.4, 63.6, 56.8, 41.4, 35, 54.2, 24.4, 56, 58.2, 76.8, 84.2, 79.4, 42.2, 81.8, 29.2, 15.8, 33.8, 40.2, 51.2, 41.2, 60.2, 88.2, 44.6, 64.4, 74, 71)

( 34.2 90 100.4 24.6 107.4 63.6 56.8 41.4 35 54.2 24.4 56 58.2 76.8 84.2 79.4 42.2 81.8 29.2 15.8 33.8 40.2 51.2 41.2 60.2 88.2 44.6 64.4 74 71 )


b=(92.9, 52, 63.1, 118.5, 37.7, 102.2, 62.9, 53.8, 101., 68.6, 51.5, 46.4, 45.2, 76., 56.1, 77.6, 61.6, 78.3, 66.3, 31.1, 71.1, 73.5, 67.6, 52.4, 47.2, 59.3, 97.5, 27.2, 81.2, 24.8, 71., 97.3, 92.6, 56, 62.3)

( 92.9 52 63.1 118.5 37.7 102.2 62.9 53.8 101.0 68.6 51.5 46.4 45.2 76.0 56.1 77.6 61.6 78.3 66.3 31.1 71.1 73.5 67.6 52.4 47.2 59.3 97.5 27.2 81.2 24.8 71.0 97.3 92.6 56 62.3 )


ci_twosample_tpooled(a, b, .95)


Two-Sample Pooled-T Test.

Confidence interval for the difference of two means.

Confidence level : 0.95 (95%)

Results:

m1 : 57.48000000000001

m2 : 66.3942857142857

s1 : 23.952804169579117

s2 : 22.261123364407695

sp : 23.05525690050534

Interval  : (-20.377370218853596, 2.5487987902822162 )

Margin of error : 11.463084504567906





NOTE: The data used in this example was taken from the textbook Introductory Statistics 6th Ed. by Neil A. Weiss with kind permission of Addison Wesly Longman, Inc. (AWL). AWL does not endorse nor it supports the Calcugator.