Foundations of Statistics
What Statistics Studies
Statistics in practice
Statistics is the science of collecting, organizing, analyzing, and interpreting data to support decisions under uncertainty. It helps answer questions like: What is typical?, How variable is the data?, Is a difference real or just random noise?
Core terms
Why statistics matters
The goal is rarely to describe data alone; it is to make reliable inferences, quantify uncertainty, and communicate conclusions clearly.
A standard statistical workflow
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Step 1: Define the question and identify the population of interest.
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Step 2: Collect data using an appropriate sampling or experimental design.
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Step 3: Summarize the data with graphs and numerical measures.
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Step 4: Model uncertainty and test hypotheses or estimate parameters.
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Step 5: Interpret the results in context and state limitations.
Descriptive vs inferential statistics
Descriptive statistics
- Summarize observed data
- Use tables, graphs, averages, and spread measures
- Does not generalize beyond the data set
Inferential statistics
- Use sample data to learn about a population
- Includes confidence intervals and hypothesis tests
- Quantifies uncertainty from sampling
Which statement best describes a statistic?
A statistic is computed from sample data, while a parameter describes a population.
Correct answer: A numerical summary of a sample
In one sentence, distinguish a population from a sample.
The population is the complete target set; the sample is the observed part used for analysis.
Correct answer: A population is the full group of interest, while a sample is a subset taken from that group.