Introduction to Statistics: Key Terms, Variables, Sampling Techniques, and Data Collection

Comprehensive vocabulary flashcards covering foundational statistical concepts, data types, measurement scales, probability and non-probability sampling methods, and data collection procedures.

Population

All individuals or items that a study aims to analyze or draw conclusions about (e.g., all students in a university).

Sample

A subset or portion of the population selected for analysis (e.g., 100 randomly chosen students from the university).

Sampling Frame

A complete list of the population from which a sample is chosen (e.g., a list of all students in the university).

Variable

A characteristic or attribute that can take on different values, such as height, weight, age, and test scores.

Data

Facts or information collected for reference or analysis, which can be numbers, words, measurements, or observations.

Parameter

A numerical value that describes a characteristic of an entire population (e.g., the true average height of all students in a school being $165\,\text{cm}$).

Statistic

A numerical value that describes a characteristic of a sample, which is a subset of the population (e.g., an average height of $164\,\text{cm}$ calculated from a sample of 50 students).

Sample Survey

A survey that collects data from a sample (a portion) of the population, rather than the entire population.

Census

A survey that collects data from every single member of the population.

Pilot Study / Pilot Survey

A preliminary survey conducted before the actual survey to test survey design, questions, and process, helping to identify any problems before the main survey is carried out.

Descriptive Statistics

The branch of statistics that involves collecting, organizing, summarizing, and analysing or displaying data using tables, charts, and averages.

Inferential Statistics

The branch of statistics that uses sample results to make conclusions, predictions, or inferences about a population.

Primary Data

Information collected directly from original sources for a specific research purpose or study, gathered firsthand by the researcher.

Secondary Data

Secondhand data or information that has already been collected and recorded by someone else for a different purpose and is reused for a new research study.

Qualitative (Categorical) Data

Data that describes categories or qualities that cannot be measured numerically (e.g., gender, nationality, eye colour, blood types, type of car).

Quantitative (Numerical) Data

Data that consists of numerical values, which can be further classified into discrete or continuous data.

Discrete Data

Quantitative data consisting of countable, whole numbers (e.g., number of students, number of cars in a parking lot, number of siblings).

Continuous Data

Quantitative data that is measurable and can take any value within a range, including decimals, percentages, and fractions (e.g., height, weight, temperature, distance, time in seconds).

Nominal Scale

A level of measurement where data can only be categorized or labeled without any quantitative order (e.g., colours, names, political party affiliation).

Ordinal Scale

A level of measurement where data can be ordered or ranked, but differences between values are not meaningful (e.g., socioeconomic status, education level, competition ranks such as 1st, 2nd, and 3rd place).

Interval Scale

A level of measurement with meaningful differences between values but no true zero point (e.g., temperature in Celsius, pH level).

Ratio Scale

A level of measurement with meaningful differences between values and an absolute, true zero (e.g., weight, height, time taken in minutes).

Sampling

The process of selecting a subset of individuals or observations from a larger population to estimate characteristics of the whole population.

Probability Sampling

A category of sampling techniques where every member of the population has a known, non-zero chance of being selected.

Simple Random Sampling

A probability sampling technique in which every member of the population has an equal chance of being selected (e.g., using a random number generator or lucky draw).

Systematic Sampling

A probability sampling technique that involves selecting every $k\text{th}$ member from a list after randomly choosing a starting point, where $k = \frac{N}{n}$.

Stratified Sampling

A probability sampling method where the population is divided into homogeneous strata based on a specific characteristic, and random samples are drawn proportionally from each stratum.

Cluster Sampling

A probability sampling method where the population is divided into heterogeneous clusters (often geographical), entire clusters are randomly selected, and all members in those chosen clusters are surveyed.

Non-Probability Sampling

A sampling method in which not all members of the population have a chance of being included, often used when probability sampling is impractical or impossible.

Convenience Sampling

A non-probability sampling technique where participants are selected based on their availability, accessibility, and ease of reach.

Judgmental Sampling

A non-probability sampling method (also called purposive or authoritative sampling) where the researcher uses their personal judgment to select individuals based on their expertise or relevance to the study.

Snowball Sampling

A non-probability sampling technique where existing study participants recruit future participants from among their acquaintances, useful for hard-to-access populations.

Quota Sampling

A non-probability sampling technique where the researcher ensures representation of specific characteristics by setting predetermined quotas for different groups within the population.

Personal Interview

A data collection method involving a face-to-face conversation where questions are asked directly, allowing for detailed responses and rapport building.

Telephone Interview

A data collection method where questions are asked over the phone to quickly and cost-effectively reach a wider geographic area.

Online Survey

A data collection method consisting of a set of self-administered questions distributed electronically via online platforms or email.

Direct Observation

A data collection method that involves recording behavior or events as they occur naturally, providing real-time data without relying on self-reporting.