文档介绍：Independent Two-Sample t-Test
Independent Two-Sample t-Test
Example 2 Plastic Strength
Problem Data set
pany makes plastic cases for calculators. You need
pare plastic samples from two suppliers for strength.
Supplier A claims to have a stronger plastic, but it costs more
than Supplier B’s plastic. Name Data type Variable type
SupplrA Numeric Response
Data collection
SupplrB Numeric Response
Pellets from randomly selected batches of plastic are pressed
into wafers of uniform thickness. Breaking strength (in psi,
pounds per square inch) is recorded for each wafer.
Tools
Stat ➤ Basic Statistics ➤ Normality Test
Stat ➤ Basic Statistics ➤ 2 Variances
Stat ➤ Basic Statistics ➤ 2-Sample t
t-Tests and Tests of Proportions Copyright Minitab Inc. 2000. All rights reserved. Rel13 Ver 2-12
Independent Two-Sample t-Test
Independent two-sample t-test
What is an independent two-sample t-test Why use an independent two-sample t-test
An independent two-sample t-test helps you determine An independent two-sample t-test can help answer questions
whether two population means are the same. such as:
The test uses the sample standard deviations to estimate σ for • Are the products of two parable?
each population. If the difference between the sample means • Is one formulation of product better than another?
is large relative to the estimated variability within the
populations, then the population means are unlikely to be the For example,
same. • Is the viscosity of oil from two different vendors similar?
An independent two-sample t-test can also be used to • Is one ink formulation brighter than another?
evaluate whether the means of two populations are different
by a specific amount.
When to use an independent two-sample t-test
Use an independent two-sample t-test when you have
continuous data from two independent random samples.
Samples are independent if observations from one-sample
are not related to the observations in