Sampling Techniques2
Sampling Techniques2
Sampling Techniques2
1 SAMPLING
Concept of Sampling
Sampling is the process of selecting units, like people, organizations, or objects from a
population of interest in order to study and fairly generalize the results back to the population
from which sample was chosen.
ADVANTAGES OF SAMPLING
1. Reduced Cost
2. Greater Speed
3. Greater Scope
4. Greater Accuracy
Proportional Allocation (PA) – the sample sizes from the different strata are proportional
to the sizes of the strata. In general, a population of size N is divided into k strata of size
N 1 , N 2 , N 3 … … , N k , and a sample of size n1 from the first stratum is taken, a sample of size n k ,
from the k th stratum is taken.
Ni
Formula: PA= ∗n
N
N = population
n = sample size
Example: Given is the enrollment data of CvSU-CBE for first semester, SY 2009-2010.
PROGRAM Ni EA PA
BSIT 420
BSCS 210
BSBM 300
BSE 40
ABPS 40
BENT 25
BSHRM 400
TOTAL(N) 1435
Select a sample of 200 students using Equal and Proportional Allocation
Where: N = population
n = sample size
Expert Sampling
Expert sampling involves the assembling of a sample of persons with known or demonstrable
experience and expertise in some area. Often, expert sampling is done when it would be the best
way to elicit the views of persons who have specific expertise.
Quota Sampling
In quota sampling, respondents are selected non-randomly according to some fixed quota.
Heterogeneity Sampling
Heterogeneity sampling is performed when all opinions or views about a specific topic are the
primary concern and representing these views proportionately is not of major importance.
Snowball Sampling
In snowball sampling, the process starts by identifying someone who meets the criteria for
inclusion in the study. The respondent is then asked to recommend others whom they may know
who also meet the criteria.
Name:_________________________________ Score:___________________
Course/Year/Section:_____________________ Teacher:_________________
Exercise 2.2
Identify the type of sampling used in the following statements.
1. An engineer selects every 50th cell phone from the assembly line for careful testing and
analysis.
__________________________________________________________________________
2. A reporter writes the name of each senator on a separate card, shuffles the cards, and then
draws five names.
__________________________________________________________________________
3. The dean at CvSU-CBE surveys all students from each of the 12 randomly selected classes.
__________________________________________________________________________
4. A reporter obtains sample data from readers who decide to mail in a questionnaire printed
in the latest issue.
__________________________________________________________________________
5. A mathematics professor selects 18 men and 18 women from each of the four classes.
__________________________________________________________________________
6. In conducting research for a psychology course, a student of CvSU-CBE interviews students
who are leaving the CBE building.
__________________________________________________________________________
7. A reporter obtains numbered listing of the 1000 companies with the highest stock market
values, uses a computer to generate 20 random numbers between 1 and 1000, and then
interviews the chief executive officers of the companies corresponding to these numbers.
__________________________________________________________________________
8. A medical student at DLS-UMC interviews all diabetic patients in each of 15 randomly
selected hospitals in the country.
__________________________________________________________________________
9. A researcher interviews every 45th patients in the list of in-patients.
__________________________________________________________________________
10. A student interviews school principals and classroom teachers about the implementation
of the 2002 Basic Education Curriculum.
__________________________________________________________________________