PRACTICAL RESEARCH 2
MODULE 4- LESSON 2
SAMPLING PROCEDURE AND THE SAMPLE
OBJECTIVE
Know the different sampling procedure;
Describe the sample of the study; and
Select appropriate sampling procedures
POPULATION AND SAMPLE
POPULATION is the totality of all the objects, elements,
persons, and characteristics under consideration.
The representative subset of the population refers to the
SAMPLE.
SAMPLING PROCEDURES
the systematic process of selecting the group to be
analyzed in the research study. The goal is to get
information from a group that represents the target
population. Once a good sample is obtained, the
generalizability and applicability of findings increases.
SAMPLING PROCEDURES
HEURISTICS VS. LITERATURE REVIEWS VS. FORMULAS
rule of the thumb for
sample size.
Descriptive: 10-20%
Comparative: 15
groups/ subjects
Survey: 800
Correlation: 100-200
Ex post facto: 30+
Experimental: 30+
Read similar studies
and analyze how
these studies used
sampling
procedures. This
increases your
study’s validity
Establishing sample
size from scratch
-Slovin’s Formula
SLOVIN’S FORMULA
SLOVIN’S FORMULA
Example: calculate the number of respondents if the total population is 300 and the
margin of error is 5%.
n=
300____
1+300(.05)2
n= 300
1.75
n= 171.43~ 171
* The number of sample is 171.
PROBABILITY SAMPLING
SIMPLE RANDOM SAMPLING
The chance of selection is the same for every member of the
population.
-Draw lots, random number generator
PROBABILITY SAMPLING
SYSTEMATIC RANDOM SAMPLING
Follows procedure in doing random selection of the samples.
(every nth element)
nth=N/n.
*The sample is nth of every population.
PROBABILITY SAMPLING
SYSTEMATIC RANDOM SAMPLING
Example: Suppose you have a list of 450 people and you need a sample of
45. How do you proceed with systematic random sampling.
Step 1: 450/45= 10. Every 10th of the population is the random
sample.
Step 2: Pick a number from 1 to 450 to start counting. Supposedly,
the group pick 23.
Step 3: Take all the selection as the sample. For instance, 23, 33, 43,
53, 63, 73, 83, 93, 103…
PROBABILITY SAMPLING
SYSTEMATIC RANDOM SAMPLING
Example: If you need 23 people from a list of 250 students, how will you follow
systematic random sampling?
Step 1: 250/23= 10.8~ 11. Every 11th of the population is the
random sample.
Step 2: Pick a number from 1 to 250 to start counting. Supposedly,
the group chose 5
Step 3: Take all the selection as the sample. For instance, 5, 16, 27,
38, 49, 60, 71, 82, 93, 104, 115, 126, 137, 148, 159, 170, 181,
192, 203, 214, 225, 236, 247
PROBABILITY SAMPLING
STRATIFIED RANDOM SAMPLING
The population is divided first into subpopulation called
strata. Each stratum population is given importance, as in
other groupings.
PROBABILITY SAMPLING
STRATIFIED RANDOM SAMPLING
Divide the number of population of the stratum with the
total number of population and multiply with the desired
sample size.
PROBABILITY SAMPLING
STRATIFIED RANDOM SAMPLING
Example: If there are 450 senior high school students and you
need 45 students, how will the sample proceed if stratified
random sampling is followed?
Grade 11
200
Grade 12
250
Total
450
PROBABILITY SAMPLING
STRATIFIED RANDOM SAMPLING
Solution: Divide each number of students per level by the total
population of 450 and then multiply by the desired sample size
of 45.
Grade 11
200/450 x 45= 20
Grade 12
250/450 x 45= 25
Total
45
PROBABILITY SAMPLING
CLUSTER SAMPLING
Large Scale survey method. It is used when the target
respondents in a research study is spread across a
geographical location. The population is divided into clusters
which are mutually exclusive.
EXERCISE:
1. Using Slovin’s formula, calculate the number of respondents if the total population is 500
and the margin of error is 2%.
2. If you need 20 respondents from 45 total population, list the sample using systematic
sampling if you would start listing from number 4.
3. Using stratified sampling, determine the sample if you need 50 people from the following:
Vegetable vendor
32
Fruit vendor
25
Fish vendor
20
Pork vendor
15
Total
92
ACTIVITY: IDENTIFY AND EXPLAIN
Sample Situation
Alex’s target population for
his study are the employees
of hotels in Mindanao. Since
there are too many
employees in these
establishments, he randomly
selected ten hotels. And then
he considered all employees
as participants in his study.
Sampling
Procedure
Justification
ACTIVITY: IDENTIFY AND EXPLAIN
Sample Situation
Dianne wants to know if the
new learning modalities in
the first semester affects the
academic performance of
senior high students. He took
all the lists of all students in
her school and
selected every 6th name to
be part of her study.
Sampling
Procedure
Justification
ACTIVITY: IDENTIFY AND EXPLAIN
Sample Situation
Faye wants to survey all the
parents in Cagayan de Oro
who opt to enroll their
elementary children to an
online class. All in all there
26,000 parents. Faye
decided to have 450 from
the target population.
Sampling
Procedure
Justification
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