Introduction to statistics
- Definition: Collect, organize, analyze, interpret, and present data; typically start from a population
- Two areas: Descriptive (to summarize and describe) vs. inferential (to make conclusions).
- Applied statistics supports decisions in medicine, IT, engineering, finance, marketing, accounting, business.
Pie charts
- Purpose: Show parts of a whole at a point in time; good for percentages, not trends. Parts: title, legend, data.
- Formula: Angle = (part/total) × 360; example: 10/40 × 360 = 90°.
- Uses: Sales composition, school time allocation, yearly spending mix.
Bar and column charts
- Bar chart: Categorical values with bar lengths proportional to values; vertical or horizontal; components: title, scale, labels, bars, legend/notes, data values.
- Column chart: Comparisons and changes over time; categories on x‑axis, values on y‑axis; grid lines for tracing values.
- Differences: Same function, different orientation; bar extends right from vertical axis, column extends up from horizontal axis; bar for many categories, column for fewer.
Histograms and frequency tables
- Histogram: Frequencies over continuous bins; reveals distribution shape, common outcomes, symmetry, deviations; x = intervals, y = frequency; bar height = frequency, width = bin width.
- Frequency table: Ascending data/intervals with counts (f); inputs to histograms. Components: class limits, class size, class marks, class boundaries.
- Discrete vs. intervals: Use histograms for class intervals; use bar/column charts for discrete categories.
Box plots
- A box plot (also called a whisker plot) is a chart that shows how data is spread out. It uses something called a five-number summary:
- Minimum → the smallest value