TYPES OF PROBABILITY SAMPLING

Question 1

STEPS IN: Simple Random Probaility Sampling

Answer 1

• Identify the complete population from which you want to draw a sample. This list should include every member to ensure comprehensive coverage
• Determine how many individuals will be included in the sample.
• Use the lottery method or the random table method

Question 2

Methods in simple random probability sampling

Answer 2

• Lottery Method: Each element is given a number then the numbers are inividually written on slips of paper.The papers are mixed thoroughly and random numbers are selcted. The participants selecte are approached for the investigation.
• Use of random table: Utilize software tools or functions (like Excel’s RAND) to select participants randomly.

Question 3

Merits of simple random

Answer 3

• it reduces chances of sampling bias
• thes ample is a good representative of the population

Question 4

Demerits of simple random sampling

Answer 4

• In many circumstances it is not possible to get or prepare an exhaustive list of elements.
• It needs a lot of efforts especially for a large population.

Question 5

STEPS IN: Systematic Random Sampling

Answer 5

• Identify the population & decide the number of partcipants in the sample.
• The sampling interval (k) is determined by dividing the total population size (N) by the desired sample size (n)
• Select a random sampling, after the first random number selcted every kth individual until the desired sample number is reached.

Question 6

Merits of systematic random sampling

Answer 6

• It can be quicker than simple random sampling since it does not require generating random numbers for each selection.
• By using a systematic approach, it reduces samling bias
• It ensures the extension of sample to the whole population

Question 7

Demerits of Systematic random sampling

Answer 7

• If the order of the list is biased in some way, systematic error may occur.
• It needs a lot of efforts especially for a large population.

Question 8

STEPS IN: Stratified Random Sampling

Answer 8

• Identify the strata- define the characteristics that make up each sub group of the population
• determine the sample size
• using a random sampling method, selct the number of participants for the investigation
• collect data and investigate

Using equal allocation technique same number of participants are drawn from each stratum regardless of the number of elements in each stratum.
Using proportional allocation technique the sample size of a stratum is made proportional to the number of elements present in the stratum.

Question 9

STEPS IN: Cluster Sampling

Answer 9

• The population is divided into clusters
• The clusters are selected randomly using systematic or simple random sampling
• All elements within the clusters are investigated

The group of elements residing in one geographical region is called as cluster.
The clusters ought to be homogenous among them on the characteristic variable of the research.

Question 10

Demerits of cluster sampluing

Answer 10

• If clusters are not homogeneous among them, the final sample may not be representative of the population.

Question 10

Merits of cluster sampling

Answer 10

• it consumes less time and effort
• In cases where the population is spread over a wide geographical region, cluster sampling is used to reduce cost as compare to simple random or systematic random sampling

Question 11

STEPS IN: Multistage Sampling

Answer 11

• Usually at the first stage target population is divided into clusters.The clusters are selected randomly.These clusters are called as first stage units or primary units. These clusters are homogenous among them but may be heterogeneous inside.
• To overcome this heterogeneity, homogenous sub groups called as strata are formed. So the strata are called the second stage units or sub-units.
• The formation of these strata can be done using cluster sampling technique or stratified random sampling technique depending on the nature of investigation. In each stratum the units may need to be further divided, for instance market places into shops, buildings into houses etc. The final units obtained are investigated.

It uses two or more sampling methods

Question 12

Advantages of Multistage Sampling

Answer 12

• it increases time and cost efficiency

Question 13

Disadvantages of multisatge sampling

Answer 13

• If the selected clusters do not capture the characteristic diversity of population, the sample would not be representative of the population
• If the characteristic variable used for making strata (in case of heterogeneity) at any stage is not appropriately selected depending on the nature of investigation, the whole research may go in vain.