MODULE
G
ALS
MODULE
FLEX Course Material
Z-TEST
College of Business and Accountancy
◦
Management Science
15

LEARNING
OUTC
MES
LESSON
Understand the
concept and use of z-
test.
Use z-test in
determining whether a
null hypothesis should
be rejected or not in
set of data that is
greater than 30.
#
15
Z-TEST

To determine whether to accept or reject the null hypothesis based on a
sample data a researcher
.

What is Hypothesis Testing?

Hypothesis Testing
is a type of statistical inference which examines
the claim about a population based on information obtained in the
random sample.
Note: In testing hypothesis about the means, the following condition
must be met:
1.
The sampling procedure used is simple random sampling.
2.
The sample is drawn from a normal or approximately normal
population.

Different cases in testing hypothesis.
1.
Hypothesis testing about means (Comparing the population mean and
the sample mean when
n ≥ 30 or n < 30).
2. Testing the difference between two sample means.
3. Testing about single proportion.
4. Testing about two proportions.

Hypothesis testing about the means
(Comparing Population Means
and Sample Means)
◦
z – test
(use z- test if the number of case, n >
30)
Formula:
◦
Where:
◦
z
- is the z-test value
◦
u
o
- is the value of the population or the hypothesized mean
◦
x̄
- is the sample mean
◦
σ
- is the population standard deviation
◦
n
- is the number of case,
n >
30
◦
Z - Test
= (x̄ – μ
o
)
/ (
σ / √n)

The critical value separates the non rejection and rejection region.

Illustrative example 1:
XYZ Corporation is a company that produces
Rina
laundry detergent and