Data refers to facts, figures, and information collected for analysis. In economics, it is used to understand and explain various phenomena.

Data collection aims to provide evidence for analyzing and solving problems, informing decisions in economics.

Secondary data is data collected and processed by another agency, such as reports, books, or websites.

A census survey includes every element of the population, providing comprehensive demographic data.

A sample survey collects data from a representative subset of the population to draw conclusions about the whole.

Random sampling selects individuals randomly, ensuring every member of the population has an equal chance of being chosen.

Non-random sampling uses subjective judgment to select samples, where not all individuals have an equal chance of selection.

Surveys can be personal interviews, mailing questionnaires, or telephone interviews, each having distinct advantages and disadvantages.

They allow for direct interaction, clarifying doubts, and collecting detailed information, though they can be expensive and time-consuming.

Mail surveys are inexpensive, can reach remote populations, and reduce interviewer bias, but may have low response rates.

They are quicker and cheaper than personal interviews, enabling real-time assistance but suffer from limited access.

A pilot survey tests the questionnaire with a small group to identify issues before full-scale data collection.

Common instruments include questionnaires, which may be structured (closed-ended) or unstructured (open-ended).

Mistakes include unclear questions, double negatives, leading questions, and ambiguous wording that can bias responses.

Sampling error is the difference between the sample estimate and the actual population parameter.

Non-sampling errors arise from systematic issues in data collection or processing, such as response biases or inaccuracies.

Census data provides comprehensive demographic information necessary for planning and policymaking in economics.

NSS stands for National Sample Survey, which conducts nationwide surveys on socio-economic issues to gather reliable data.