Rev Pertemuan 7 Populasi, Sampel & Teknik Sampling3

Summary

This lecture focuses on population, sampling, and sampling techniques in quantitative research, with an emphasis on Islamic finance studies. It explains the importance of accurately defining populations and selecting representative samples to ensure valid statistical analysis. The session covers probability sampling methods (simple random, stratified, cluster) and non-probability methods (purposive, convenience, snowball), highlighting the rationale for choosing each. Key considerations in Islamic research, including ethical principles, justice, data honesty, and transparency, are discussed. Practical guidance on determining sample size using Slovin's formula or SEM rules, and setting clear, justifiable purposive criteria, is also provided to help students design robust, credible research.

Takeaways

• 😀 A sample is a scientific representative of the population, and statistical analysis is invalid if the sample is incorrect.
• 😀 Population refers to all units of analysis that possess characteristics relevant to the research objectives, and must be defined specifically.
• 😀 Sampling must be done scientifically, with the sample being representative, accessible, and methodologically justifiable.
• 😀 Probability sampling gives every member of the population an equal chance to be selected, suitable for large surveys and generalizable research.
• 😀 Non-probability sampling involves unequal selection chances, often used in thesis or small-scale research, including purposive, convenience, and snowball sampling.
• 😀 In Islamic economic research, purposive sampling is often rational due to limited population, incomplete data, and specific Shariah criteria.
• 😀 Sampling in Shariah research must follow ethical principles: fairness, honesty, transparency, and freedom from personal or group bias.
• 😀 Sample size determination is crucial; too small reduces statistical power, too large wastes resources. Methods include Slovin’s formula, rule of thumb for regression, and SEM-specific guidelines.
• 😀 Purposive sampling criteria must be objective, measurable, and justified theoretically, ensuring alignment with research variables.
• 😀 Practical steps for determining population and sample: identify unit of analysis, define geographical and temporal boundaries, choose appropriate sampling method, justify methodology, calculate sample size, and define purposive criteria.
• 😀 Properly determined populations and samples produce valid data, forming the foundation of sound research and avoiding bias.

Q & A

What is the main topic discussed in the lecture?

The lecture discusses research methodology in quantitative research, focusing on population, samples, and sampling techniques.

Why is sample selection considered important in research?

Sample selection is important because an incorrect sample can lead to biased conclusions, making statistical analysis invalid even if the research model is correct.

What is meant by a population in research?

A population is the entire unit of analysis that possesses characteristics relevant to the research objectives.

Why must a research population be defined specifically?

A population must be defined specifically because clarity in defining the population determines the validity of the research generalization.

What is a sample in research methodology?

A sample is a subset of the population selected scientifically to represent the population.

What are the two main categories of sampling techniques?

The two main categories are probability sampling and nonprobability sampling.

What is probability sampling?

Probability sampling is a sampling technique where every member of the population has an equal chance of being selected.

Can you give examples of probability sampling methods?

Examples include simple random sampling, stratified sampling, and cluster sampling.

What is nonprobability sampling?

Nonprobability sampling is a technique where not all members of the population have the same chance of being selected, often based on specific criteria.

Which nonprobability sampling method is most commonly used in Islamic economics research?

Purposive sampling is the most commonly used method in Islamic economics research.

Why is purposive sampling often chosen in Islamic economics research?

It is chosen because Islamic economics research often involves limited populations, incomplete data, and specific Sharia-compliant criteria.

What are the ethical principles in sampling according to the lecture?

The ethical principles include fairness (al-adl), honesty in data collection, transparency, verifiability, and freedom from personal or group bias.

Why is determining the correct sample size important?

A correct sample size is important because a sample that is too small weakens statistical power, while a sample that is too large wastes resources.

What is the Slovin formula used for?

The Slovin formula is used to calculate sample size when the population size is known.

What is the general rule of thumb for regression sample size?

The general rule is to have at least 10–15 observations per variable, with 100 respondents considered ideal for robust results.

What is the recommended sample size approach for PLS-SEM?

PLS-SEM commonly uses the 10-times rule, meaning the sample size should be at least 10 times the largest number of indicators in one construct.

What are examples of purposive sampling criteria for Islamic SME research?

Examples include businesses operating for at least two years, using Islamic financing products, and having basic financial records.

Why must purposive sampling criteria have theoretical justification?

Theoretical justification ensures that each criterion is relevant to the research variables and scientifically defensible.

What are common mistakes in purposive sampling?

Common mistakes include using vague criteria, irrelevant criteria, and failing to provide theoretical justification for the selected criteria.

What is an example of a poor sampling criterion versus a good one?

A poor criterion is 'successful SMEs' because it is subjective, while a good criterion is 'annual turnover of at least a certain amount' because it is measurable and verifiable.

What steps should students follow when determining a population and sample?

Students should identify the unit of analysis, determine geographic and temporal boundaries, choose an appropriate sampling technique, and provide methodological justification.

What elements must be included in the methodology section related to population and sampling?

The methodology section should include the unit of analysis, population characteristics, geographic and temporal boundaries, population size if known, sampling technique, and sample size justification.

What is the lecturer’s main message about population and sampling?

The lecturer emphasizes that correct sample determination is the foundation of valid research and should never be underestimated.