Box Plot Comparison
Visually compare distributions across multiple groups. The box shows the Q1-Q3 interquartile range, the center line is the median, whiskers extend to the non-outlier extremes, and outliers are marked individually.
The QC department wants to compare whether part dimension distributions are consistent across shifts A, B, and C. Side-by-side box plots show each shift's median, IQR, and outliers, so the supervisor can see at a glance which shift is most stable and which has anomalies to investigate. Unlike tables, box plots handle unequal sample sizes per shift well and let you visually compare up to 5-10 production groups on one chart.
Each shift measures 30 parts: Shift A: median 10.02 mm, IQR=0.12, no outliers Shift B: median 9.95 mm, IQR=0.30, 1 low outlier (9.62) Shift C: median 10.08 mm, IQR=0.15, 2 high outliers (10.51, 10.48) → Shift B has the largest variation (widest IQR); investigate operator skill differences → Shift C's outliers exceed USL=10.40; investigate root cause
FAQ
Related Tools
Histogram & Normality Test
Box plots show group comparisons and outliers; histograms show distribution shape. Use both for a complete picture of your data.
Open toolOne-Way ANOVA
After visualizing group differences with a box plot, use ANOVA for a formal statistical test of whether group means differ significantly.
Open toolMann-Whitney U Test
When the box plot shows skewed distributions or outliers, Mann-Whitney compares two groups without assuming normality.
Open tool