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Questions and Answers

What is the main goal of stratified sampling?

To select a larger sample size from each stratum

To ensure the sample is internally heterogeneous

To minimize costs while maximizing efficiency (correct)

To create strata that are heterogeneous with respect to one another (correct)

In a stratified multi-stage design, what characteristic should the first-stage units have?

They should be large clusters of subunits only

They should be selected from an external population

They should be internally heterogeneous and homogeneous with respect to one another (correct)

They should be representative of the entire population

What is a sampling frame primarily used for?

To define the population's parameters

To solely estimate population variance

To determine the random assignment of units

To list the units from which the sample is selected (correct)

Which of the following is true regarding the population mean in two-stage sampling?

It can be influenced by the internal homogeneity of the strata Signup and view all the answers

What characterizes an effective sampling frame?

It is an accurate representation of the entire population Signup and view all the answers

In the context of sampling methods, what does 'probability proportional to size' refer to?

Selecting units that contribute larger values to the overall population Signup and view all the answers

What principle is crucial for forming strata in stratified sampling?

Strata should be formed to be internally homogeneous Signup and view all the answers

What is one key advantage of using a stratified multi-stage sampling approach?

It allows for more detailed analysis without increasing sample size excessively Signup and view all the answers

What are the first stage sampling units called in a multistage sample design?

Primary sampling units (PSUs) Signup and view all the answers

Which type of sampling frame consists of various geographical units such as counties and districts?

Area frames Signup and view all the answers

What is the main purpose of a master sample frame?

To establish coverage areas for multiple surveys Signup and view all the answers

Which property is essential for minimizing coverage error in a sampling frame?

Well-defined units Signup and view all the answers

Secondary sampling units in a three-stage design are referred to as what?

Secondary sampling units (SSUs) Signup and view all the answers

What type of frame is used when there is not a sufficient population frame for ultimate sampling units?

Clustered frames Signup and view all the answers

What is a key feature required for the identifiers of frame units?

Both primary and secondary identifiers Signup and view all the answers

What defines the ultimate sampling units (USUs) in a household survey?

Housing units (households) Signup and view all the answers

What is the primary reason to know the proportion to be studied when calculating sample size?

To apply the sample size formula correctly Signup and view all the answers

If no prior information about the proportion is available, what value should be used for p?

0.50 Signup and view all the answers

What does the variable w represent in the sample size calculation formula?

The allowed margin of error Signup and view all the answers

Which confidence level is commonly used when estimating population proportions?

95% Signup and view all the answers

In the context of sample size calculations, what does Zα/2 represent?

The critical value for the chosen confidence level Signup and view all the answers

What factor does NOT influence the required sample size according to the provided information?

The age of the population studied Signup and view all the answers

If a hospital administrator wants a margin of error of 3% with a 95% confidence level and has no prior proportion data, how many patients should be surveyed?

1067 patients Signup and view all the answers

Why is it important to decide the sample size during the planning stage of a survey?

To achieve the desired level of precision for estimates Signup and view all the answers

What is the impact of using an effective sample size in a survey?

It helps generate useful estimates. Signup and view all the answers

How is the population estimate derived in a survey?

By multiplying the sample estimate by the inverse of the sampling fraction. Signup and view all the answers

Which of the following is NOT a method of primary data collection?

Historical documents Signup and view all the answers

What type of data is defined as data collected under the direct supervision of the researcher?

Primary data Signup and view all the answers

Which of the following sources would typically provide secondary data?

Data found in various publications Signup and view all the answers

What is a major objective in estimation procedures for surveys?

To improve the precision of population estimates Signup and view all the answers

Ethics is primarily a study of which of the following concepts?

Value concepts of good and bad Signup and view all the answers

Which statement about secondary data is correct?

It can be published and is collected for other purposes. Signup and view all the answers

What does the ethical principle of honesty require researchers to do?

Report data and findings truthfully Signup and view all the answers

Which ethical principle emphasizes the importance of respecting individual choices in research involving human participants?

Respect for persons Signup and view all the answers

According to research ethics, what is the obligation of researchers regarding beneficence?

To maximize benefits and minimize harms Signup and view all the answers

In the context of research ethics, what does the principle of justice refer to?

Treating each person according to what is morally right Signup and view all the answers

What is a key aspect of the integrity principle in research ethics?

Keeping promises and agreements made with colleagues Signup and view all the answers

Which ethical principle aims to minimize errors and emphasize careful examination of research?

Carefulness Signup and view all the answers

What does the openness principle in research ethics encourage?

Sharing data and being open to criticism Signup and view all the answers

How should researchers treat animal subjects according to ethical guidelines?

With the same respect they would treat human subjects Signup and view all the answers

What is a major reason for the importance of questionnaire design in a formal sample survey?

It ensures data collected is of high quality. Signup and view all the answers

Which principle should be followed regarding the content of a questionnaire?

Incorporate the minimum number of topics necessary to meet objectives. Signup and view all the answers

What is essential for maintaining clarity and comprehensiveness in a questionnaire?

Ensuring questions are clear and easy to understand. Signup and view all the answers

What sequence of activities is recommended when designing a questionnaire?

Identify question topics, phrase information, and list logically. Signup and view all the answers

Why must the time for interviews be kept reasonable in questionnaire design?

To ensure that a reasonable number of questions can be covered. Signup and view all the answers

What does it mean for a questionnaire to be self-contained?

It includes identification of enumerator and relevant details. Signup and view all the answers

What is the purpose of testing the questionnaire design on model respondents?

To identify and modify issues before the pilot survey. Signup and view all the answers

What should be recorded for each question in a questionnaire?

The method for recording the interview response. Signup and view all the answers

Study Notes

Multistage Sampling: Two-Stage Equal Cluster Sampling

Multi-stage sampling selects a sample in stages.
Sampling units in each stage are sub-sampled from previous stages.
Selection methods include simple random sampling, systematic sampling, and probability proportional to size.

Multistage Sampling - Reasons

Sampling frames may not be available for all units.
Multi-stage sampling is more practical when frames are incomplete or expensive to construct.
Multi-stage sampling can be more convenient, especially in large-scale surveys.
Reduced response errors and improved sampling efficiency by lowering intra-class correlation in groups like villages and households.

Multistage Sampling - Example

In a crop survey, villages are first-stage units.
Fields within villages are second-stage units.
Plots within fields are third-stage units.

Multistage Sampling - Population Diagram

Population includes a large number of units categorized into clusters.
First-stage: select a small number of clusters.
Second-stage: sample a number of units (e.g., m units) from each selected cluster.

Multistage Sampling - Equations

Population Mean: Y = (1/NM) Σ_i=1^N Σ_j=1^M Y_ij
Mean per first-stage unit (fsu): (1/NM) Σ_i=1^N Σ_j=1^M Y_ij
Mean per second-stage unit in the population: (1/NM) Σ_i=1^N Σ_j=1^M Y_ij.

Multistage Sampling - Calculation Average

Average the estimator over all second-stage selections from a fixed set of n units.
Then average over all possible selections of n units by the plan.

Multistage Sampling - Variance Calculation

Two-stage variance: Var(θ) = E[E₂(θ-θ̂)²]
Includes the variance of the estimator and the average over the second-stage selections.

Multistage Sampling - Three-stage Variance

Variance of three-stage sampling: Var(θ) = V₁[E₂(θ₃)] + E₁[V₂(θ₃)] + E[E₂{V₃(θ₃)}].

Stratified Multistage Sampling

Stratified multistage designs combine advantages of stratification and multi-stage sampling.
Strata should be internally homogeneous but heterogeneous with respect to each other.
First-stage units should be internally heterogeneous but homogeneous relative to each other.

Sampling Frames - Definition

A listing of units from which a sample will be selected in any stage of sampling.
Accurate representation of the target population.
Contains materials, procedures, and devices to identify, distinguish, and allow access to population elements.

Sampling Frames - Content

Auxiliary information is included (measure of size, demographic information).
Used for special sampling techniques (stratification, probability proportional to size, etc.).
Needed for each stage of selection in multi-stage sample designs.

Frames in Multi-stage Design

Primary Sampling Units (PSUs) are used at the first sampling stage.
Secondary Sampling Units (SSUs), Third-stage units, etc. are for intermediate sampling stages.
Ultimate Sampling Units (USUs) refer to the sampling units at the final stage, often the ultimate units of interest.

Sampling Frames - Examples

In a three-stage household survey, districts could be PSUs, enumeration areas SSUs, and households USUs.

Types of Sampling Frames

Area frames: County, district, tract, etc.
List frames: Lists of target units.
Master Sample frames: Stable frames for multiple survey rounds.
Clustered frames: Used when no good or inexpensive population frame is available.

Desirable Properties of Sampling Frames

Quality related: completeness (coverage), up-to-date, and stable units.
Efficiency related: choice of sampling units, hierarchical structure, and good quality maps and easy manipulation.

Frame development, maintenance, and updates.
Cost should be considered and budgeted in the survey's planning stages.
The frame source with the lowest development, use, and maintenance cost is preferred when equivalent in quality and efficiency.

Sample Design

The goal of sampling is representative target population.
Prior knowledge of the population is needed for reasonable estimations.
Sampling method affects sampling estimate precision and accuracy.

Sample Design - Choice of Design

Survey statisticians and experts collaborate for a design.
Issues like objectives, variables to be measured, required estimates, reliability, validity, timeliness, and costs need agreement.

Sample Design - Objectives and Prelim Investigation

Define the problem clearly.
Define the population to be studied, including geographic area, economic or social classification.
Specify desired information in statistical terms.

Sample Design - Level of Breakdown and Timeliness

Specify breakdown levels (regions, age, sex) for tabulated results.
Specify the accuracy level or the tolerated error rate.
Determine the required timeliness of the results.

Sample Design - Selection Process

Choose sample design after survey objective, coverage, and issue assessments.
Various sample designs may be suitable for different survey types and circumstances.

Sample Size Calculation - Population Proportion

Formula for sample size: n = (Z_α/2)² * p(1-p) / w²
p: Estimate of population proportion; reasonable estimate or 0.50 if unknown.
w: acceptable width of confidence interval.
Z_α/2: Z-value related to confidence level; often 1.96 for 95% confidence.

Sample Size Estimation - Factors

Required precision in the estimate: specify desired margin of error and confidence level.
Sample design: different designs affect precision for the same sample size.

Sample Size Estimation - Calculation Basis

Minimum sample size is required for acceptable precision.
Accurate implementation is essential for sample representation and reliable estimates.
Varied precision requirements across variables lead to different sample size needs.

Estimation Procedure

Purpose of surveys is estimated population characteristics.
Estimates along with precision from sampling variance are reported.
Calculation of estimates depends on the sampling design.

Data Collection Methods

Primary data: data collected directly for the survey.
Typical methods are questionnaires, interview methods, and observation method.
Secondary data: data collected previously for a different purpose.

Data Collection - Secondary Data Sources

Published sources (journals, books, historical documents).
Other sources of published information.

Ethical Considerations

Systematic study of values (good, bad, right, wrong).
Focus on principles and conduct standards.

Codes & Policies for Research Ethics

Professional associations set ethical codes for research practices.
Specific ethical principles include honesty, objectivity, integrity; respect for persons, beneficence, and justice.
Ethical review boards ensure research's scientific merit and ethical concerns' resolution.

Process where participants make voluntary choices to be in the study.
Goal is for participants to understand and freely choose to participate or continue.
Essential elements are information, comprehension, and participant autonomy.
Considers objectives, voluntary participation and withdrawal, details of discomfort, and risk, expected costs and benefits.

Chapter 6 - Instruments of Data Collection

Data collection instrument is used to gather data.
Two types exist: structured and unstructured questionnaires.

Type of Questionnaires

Structured questionnaires: Written questions, respondents respond directly.
Unstructured questionnaires (checklist of topics) : Used for qualitative surveys.

Questionnaire Design Principles

Questions should be clear, unambiguous, same meaning for all.
Neutral phrasing is crucial; avoid leading questions.
Use simple language that aligns with respondents' native language.

Questionnaire Design Principles - Sensitive Topics

Awareness of sensitive topics that may hinder open answers.
Proper structure and design are essential to ensure reliability.

Types of Questions

Closed-ended questions: Pre-determined answers (dichotomous, multiple choice).
Open-ended questions: Unstructured, respondents answer freely in their own words.

Question Layout

Logical order for questionnaires.
Common layouts: verbatim listing, question listing, tabular row and column format, and checklist of topics.

Common Problems of Question Phrasing

Use clear, unambiguous wording and appropriate meaning to all parties.
Avoid wording questions that lead respondents to specific answers.

Multiple Questions

Multiple questions combine two or more distinct questions in one.
Avoid ambiguity in the construction of questions.
The wording needs to be precise and accurately reflect the intended meaning for all respondents.

Choice of Reference Period

Accurate time reference period in questionnaire design is important.
Time-reference period refers to the specified time frame for gathering information on events.

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