[06.04b] Sampling Methods and Designs (Part 2) V2.1.pdf

Stratified Sampling

What sampling method involves organizing the sampling frame into separate "strata" if the population embraces distinct categories?

Independent sub-population

What is each stratum treated as in stratified sampling?

Randomly selected

How are individual elements selected out of each stratum?

The same chance of being selected

What chance does every unit in a stratum have?

Proportionate representation

What does using the same sampling fraction for all strata ensure?

Varying sampling fraction between strata

How can adequate representation of minority subgroups of interest be ensured in stratified sampling?

Different sampling approaches can be applied to different strata

What is possible because each stratum is treated as an independent population?

If there has been stratification in the community (e.g., rural and urban areas)

When might stratified sampling be considered for adequate representation?

Random sampling

What type of sampling is employed independently in urban and rural areas after stratification?

To assess if the regions are different from each other

In a national sense, why might stratification according to regions be needed?

Poverty

What is an example of a characteristic where regions can be more similar?

Logistical consequences

What factor must be considered when grouping populations into strata, as it may require visiting all regions independently?

To ensure equal representation

Why may stratification be needed if very different groups, such as men and women in private schools, are involved?

Sampling frame of the entire population

What must be prepared separately for each stratum, which is a drawback of stratified sampling?

Complicating the design

What happens if stratifying variables are related to some multiple criteria but not others?

Potentially requires a larger sample

What is a drawback of stratified sampling in designs with a large number of strata or a specified minimum sample size per group?

Poststratification

What is the term for stratification sometimes introduced after the sampling phase?

You did not ensure power in each stratum

What is the main problem with poststratification?

Sample size of each stratum was not computed and allocated properly

What specific sample size issue arises in poststratification?

A lack of prior knowledge of an appropriate stratifying variable

What is one reason poststratification might be implemented?

When the experimenter lacks the necessary information to create a stratifying variable during the sampling phase

What is another reason poststratification might be implemented?

Simple random sample

What type of sampling does implementation of poststratification usually follow?

To implement weighting, which can improve the precision of a sample's estimates

In addition to allowing for stratification on an ancillary variable, what can poststratification be used for?

Cluster sampling

What sampling method might be considered if a community is divided into zones (clusters) whose characteristics are not significantly different from each other?

Two-stage sampling

What type of sampling is cluster sampling an example of?

A sample of areas is chosen

What happens in the first stage of cluster sampling?

A sample of respondents within those areas is selected

What happens in the second stage of cluster sampling (in the general definition)?

Geographical contiguity

What are clusters of homogenous units usually based on?

Groups rather than individuals

What are the sampling units in cluster sampling?

All units from the selected clusters are studied

What happens to the units from the selected clusters in classic cluster sampling?

EPI (Expanded Program on Immunization)

What health program often uses cluster sampling to evaluate vaccination coverage?

Cuts down on the cost of preparing a sampling frame

What is one advantage of cluster sampling regarding costs?

Can reduce travel and other administrative costs

What is another advantage of cluster sampling related to logistics?

Sampling error is higher for a simple random sample of the same size

What is a disadvantage of cluster sampling regarding sampling error?

Increase sample size

What is the solution to the higher sampling error in cluster sampling?

Whatever your computed sample size must be increased at some point

What must be done to the sample size in cluster sampling?

To sample everyone within the cluster

What was the reason cluster sampling was being disregarded in a nutrition project, based on the lecturer's experience?

Selecting a group of people at different stages

What is a general description of cluster sampling based on the lecturer's definition?

One-stage sampling

What type of cluster sampling includes all elements within selected clusters in the sample?

Barangay

What is an example of a cluster in one-stage sampling in a city?

Two-stage sampling

What type of cluster sampling involves randomly selecting a subset of elements within selected clusters for inclusion in the sample?

Zones or streets within the barangay

What is an example of the second cluster sampled in two-stage sampling?

Individual or household

What can the sampling unit be at a community level?

The unit of analysis

What can the household be considered if it is the sampling unit and individuals inside are not further sampled?

Non-overlapping subsets of the population

What characteristic do strata and clusters share?

One household can only be considered part of Region 1, and not Region 3

What example illustrates that strata and clusters are non-overlapping and mutually exclusive?

All strata are represented in the sample

What is true about the representation of strata in the sample?

Only a subset of clusters are in the sample

What is true about the representation of clusters in the sample?

Homogeneous

What characteristic describes groups whose characteristics are similar when considered as a cluster (e.g., Zone 1, 2, and 3)?

Variable (heterogeneous) enough to represent the different variabilities in your general population

What property should a cluster sample possess to represent the target population?

Different races, religions, and socioeconomic standing

What heterogeneous characteristics might be captured within a barangay (cluster)?

Externally heterogeneous (different)

What characteristic describes the relationship between groups in stratified sampling?

Internally homogenous (similar)

What characteristic describes the relationship within groups in stratified sampling?

Externally homogenous (similar)

What characteristic describes the relationship between groups in cluster sampling?

Internally heterogeneous (different)

What characteristic describes the relationship within groups in cluster sampling?

Type of residence, region

What are examples of stratified sampling?

Barangays, municipalities, streets

What are examples of cluster sampling?

Cluster Sampling

Which sampling method has a higher sampling error for a simple random sample of the same size?

Two-stage cluster sampling

What type of sampling involves randomly selecting a subset of elements within selected clusters for inclusion in the sample?

Multistage cluster sampling

What is a complex form of cluster sampling in which two or more levels of units are embedded one in the other?

In the national level

When is multistage cluster sampling useful because the organization of the population is complicated?

The process of taking random samples of preceding random samples

What is the technique essentially in multistage cluster sampling?

It banks on multiple randomizations

Why is multistage cluster sampling an effective strategy?

When a complete list of all members of the population does not exist and is inappropriate

When is multistage cluster sampling frequently used?

It avoids the large, and perhaps unnecessary costs associated with traditional cluster sampling

What cost advantage does multistage sampling provide over traditional cluster sampling?

Philippines Multisectoral Nutrition Project (PMNP)

What DOH and DSWD project, funded by World Bank and UNICEF, is used as an example of multistage cluster sampling?

Improvement in the stunting of children, less than six months (breastfeeding) and 6 to 23 months old

What were the indicators measured in the PMNP example?

Municipality

What was the first stage of cluster sampling in the PMNP example?

Barangay

What was the second stage of cluster sampling in the PMNP example?

Systematic Sampling of Children

What was the third stage of sampling in the PMNP example?

Multiphase sampling

What type of sampling design involves collecting required information from a large sample, and additional information from sub-samples of the whole sample?

Expensive diagnostic tests

What is a common challenge that necessitates collecting sub-samples within an established sample in multi-phase sampling?

Less costly, less laborious, and more purposeful

How is a survey by multi-phase procedure described?

There will be a loss of information

What is the consequence of performing subset analysis due to the cost of diagnostic procedures?

TB survey MT in all cases

What is the Phase I example of multi-phase sampling given?

X-Ray chest in MT positive cases

What is the Phase II example of multi-phase sampling given?

Sputum Examination in X-ray positive cases

What is the Phase III example of multi-phase sampling given?

Quota sampling

What non-probability sampling method first segments the population into mutually exclusive sub-groups, similar to stratified sampling?

Judgement

What is used to select subjects or units from each segment in quota sampling, based on a specified proportion?

An interviewer may be told to sample 200 females and 300 males between the age of 45 and 60

What is an example of a specified proportion used in quota sampling?

The second step (using judgment to select subjects)

What makes quota sampling a technique of non-probability sampling?

Non-random

How is the selection of the sample described in quota sampling?

They might be biased

What is the problem with samples in quota sampling because not everyone gets a chance of selection?

It is its greatest weakness

How is the random element (or lack thereof) described in quota sampling?

Convenience sampling

What non-probability sampling method is based on convenience and only samples those within one's capacity?

Grab sampling, opportunity sampling, accidental sampling, or haphazard sampling

What are four other names for convenience sampling?

Drawn from that part of the population which is close to hand

From where is the sample drawn in convenience sampling?

Readily available and convenient

What are two characteristics of the source of the sample in convenience sampling?

Cannot scientifically make generalizations about the total population

What is the scientific limitation of a researcher using convenience sampling?

It is not representative enough

Why can generalizations not be made from a convenience sample?

Pilot testing

What is convenience sampling most useful for?

Snowball sampling

What similar technique to convenience sampling is used in social science research, where existing subjects recruit more subjects?

Bias is not really a problem

Why is snowball sampling acceptable in social science research, which is qualitative?

Judgemental or Purposive Sampling

What non-probability sampling method involves the researcher choosing the sample based on who they think would be appropriate for the study?

When there is a limited number of people that have expertise in the area being researched

When is purposive sampling primarily used?

Random sampling

What type of sampling is always desired in quantitative research?

It ensures that everyone in the sampling population is given the chance to be selected

Why is random sampling desired in quantitative research?

Convenience sampling

What non-probability method may be done if random sampling is not possible?

Sampling frame is difficult to gather or the population is dynamic and locomotive

What are two examples of conditions where convenience sampling might be necessary?

In the limitations of your study

Where must the use of convenience sampling be stated?