Overview
This lecture introduces the basics of data collection in statistics, covering the overall process of conducting statistical research and defining key vocabulary terms used in the field.
The Process of Statistics
- First, identify the research objective by deciding the research question and the population to study.
- Collect data from the selected population using proper sampling techniques.
- Describe or summarize the data using numerical summaries, percentages, or averages.
- Perform inference by extending sample results to the broader population, accounting for uncertainty with a margin of error.
Example: Minimum Wage Study
- Research objective: Determine the percentage of adult Americans favoring an increase in minimum wage.
- Population: Adult Americans; Sample: 1009 surveyed individuals.
- Data collected: 706 out of 1009 support an increase (approximately 70%).
- Inference: Use the sample percentage with a 3% margin of error, giving a confidence range of 67% to 73%.
Key Vocabulary in Statistics
- Statistics involves collecting, organizing, summarizing, and analyzing data to draw conclusions and gauge confidence in findings.
- Population is the entire group to be studied.
- Individual is a single member of the population.
- Sample is a subset of the population used for study.
- Statistic is a numerical summary of a sample.
- Parameter is a numerical summary of a population.
- Descriptive Statistics involves organizing and summarizing data through tables, graphs, or percentages.
- Inferential Statistics uses sample data to make predictions or inferences about a population.
- Variable is a characteristic of individuals within a population.
- Qualitative Variable (Categorical) classifies individuals based on characteristics (e.g., color, class rank).
- Quantitative Variable is a numerical measure of individuals, suitable for arithmetic operations.
Types of Quantitative Variables
- Discrete Variable: Countable values (e.g., number of classes, siblings).
- Continuous Variable: Measurable, infinite values (e.g., height, weight).
Key Terms & Definitions
- Statistics — Science of collecting, organizing, summarizing, and analyzing data to answer questions.
- Population — Entire group under study.
- Individual — A single member of the population.
- Sample — Subset of the population studied.
- Statistic — Numerical summary from a sample.
- Parameter — Numerical summary from a population.
- Descriptive Statistics — Summarizing and organizing data.
- Inferential Statistics — Making predictions from sample to population.
- Variable — Characteristic of individuals in a population.
- Qualitative Variable — Classifies individuals into categories.
- Quantitative Variable — Numerically measures characteristics.
- Discrete Variable — Countable quantitative variable.
- Continuous Variable — Measurable quantitative variable with infinite possibilities.
Action Items / Next Steps
- Print and organize the guided notes, tables, and formula pages as instructed.
- Review definitions and be prepared to classify variables as qualitative or quantitative in the next lesson.