Histogram
Definition
A bar chart in which data are grouped into contiguous equal-width intervals (bins) and the bar height represents the count or relative frequency of observations in each bin. The total area of all bars equals the total count or 1.0 for a density histogram.
- Structure
- Contiguous bins, no gaps between bars
- Y-axis options
- Count (frequency) or density (relative frequency)
- Bin choice
- Bin width controls smoothing vs detail trade-off
- Common use
- Distribution shape of forensic measurement data
Common questions
How is a histogram different from a bar chart of categories?+
A bar chart plots discrete unrelated categories with gaps between bars. A histogram plots a continuous variable split into ordered, adjoining numeric ranges, so bar order and adjacency carry meaning.
Why does bin width matter in forensic reporting?+
Too few bins hides structure like bimodality, too many bins makes the shape look noisy from sampling variation. Analysts often try several widths and report the one that best represents the underlying pattern without over-smoothing or over-fitting.
Related terms
- Bandwidth
- The smoothing parameter in a kernel density estimate. A small bandwidth produces a jagged curve that follows every data point; a large...
- Box Plot (Box-and-Whisker Plot)
- A graphic showing the five-number summary of a distribution: the minimum, first quartile (Q1), median (Q2), third quartile (Q3), and maximum. Whiskers...
- Interquartile Range (IQR)
- The difference between the third quartile and the first quartile: IQR = Q3 - Q1. It measures the spread of the central...
- Kernel Density Estimate (KDE)
- A non-parametric smooth probability density function fitted to a set of measurements by placing a kernel (usually Gaussian) over each data point...
- Scatter Plot
- A two-dimensional graph in which each observation is plotted as a point at coordinates (x, y), where x and y are two...