INTRODUCTION TO PROBABILITY AND STATISTICS FOURTEENTH EDITION

INTRODUCTION TO PROBABILITY
AND STATISTICS
FOURTEENTH EDITION

Chapter 9
Large-Sample Tests of
Hypotheses

,INTRODUCTION
¢Suppose that a pharmaceutical company
is concerned that the mean potency  of
an antibiotic meet the minimum
government potency standards. They
need to decide between two possibilities:
–The mean potency  does not exceed
the mean allowable potency.
– The mean potency  exceeds the
mean allowable potency.
• This is an example of a test of
hypothesis.

,NTRODUCTION
¢Similar to a courtroom trial. In trying a
person for a crime, the jury needs to
decide between one of two possibilities:
⚫ The person is guilty.
⚫ The person is innocent.
¢ To begin with, the person is assumed
innocent.
¢The prosecutor presents evidence, trying
to convince the jury to reject the original
assumption of innocence, and conclude
that the person is guilty.

, PARTS OF A STATISTICAL
TEST
1. The null hypothesis, H0:
⚫ Assumed to be true until we can prove otherwise.
2. The alternative hypothesis, Ha:
⚫ Will be accepted as true if we can disprove H0


Court trial: Pharmaceuticals:
H0: innocent H0:  does not exceeds allowed
amount
Ha: guilty Ha:  exceeds allowed amount