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Independent Sample Rafael Mendoza
Elementary Business Statistics – Class 14 McCombs Independent Samples, Unequal Population Standard Deviations Case Unequal Population Std. Dev. σ1 = σ2 Conﬁdence Interval for Diﬀerence Between Means:
X1 − X2 ± t∗ × Standard Error for (X1 − X2 )
Standard Error: for (X1 − X2 ) = s2
n1 + s2
n2 Degrees of freedom: - complicated Use StatTools to calculate the conﬁdence interval
Example: Customer waiting at R&P Supermarket Rafael Mendoza
Elementary Business Statistics – Class 14 McCombs Tests of Signiﬁcance the return to the Normal
Distribution: the population standard deviation, σ ,
is known Rafael Mendoza
Elementary Business Statistics – Class 14 McCombs Statistical Inference Methods for drawing conclusions about a population from sample data are
called statistical inference.
2 Conﬁdence Intervals - estimating a value of a population parameter
Tests of signiﬁcance - assess evidence for a claim about a population Inference is appropriate when data are produced by either
a random sample or
a randomized experiment Rafael Mendoza
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This document was uploaded on 02/19/2014 for the course STA 309 at University of Texas at Austin.
- Fall '07