Module 1 · Descriptive Statistics · Topic 1
Statistics Defined. Statistics is the science of collecting, organizing, analyzing, and interpreting data to make informed decisions. It provides tools to transform raw data into useful information.
Two Branches. Descriptive statistics summarizes and describes data you already have. Inferential statistics uses sample data to draw conclusions about a larger population.
xbar = sum(x_i) / n — The arithmetic average of a data set.s^2 = sum((x_i - xbar)^2) / (n - 1) — Average squared distance from the sample mean with Bessel correction.A university surveys 500 students about sleep habits. Reporting that the average sleep time is 6.8 hours is descriptive statistics. Concluding that all students at the university average about 6.8 hours is inferential statistics.
Statistics is everywhere: medical research, business decisions, sports analytics, and social science. Understanding it helps you evaluate claims and make better decisions.
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