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Paste the values for each machine, shift or supplier and compare center, spread and outliers at a glance. Choose vertical or horizontal orientation and download the chart as PNG or PDF.
Pre-sizing and estimating tool: results do not replace design, calculations or reports signed by a licensed professional, nor verification against the applicable codes and standards.
How to read: each box is a group. The box holds the middle half of the values (Q1 to Q3) and the line inside it is the median, the middle value. The whiskers show how far the normal values go; red circles beyond them are outliers. Boxes at different heights = groups at different levels; a longer box = a group that varies more.
Quartiles by the Minitab method, position (N + 1)p. Whiskers to the most extreme value within 1.5 × IQR.
Minimum and maximum = smallest and largest value; Q1 and Q3 = values below which 25% and 75% of the data lie; IQR = Q3 − Q1, the box width (the larger, the more variation); 95% CI median = likely range of the true median; Outliers = values beyond 1.5 × IQR, with their spreadsheet row.
Take this page’s results to another calculator with the fields already filled in.
The calculation report gathers this page's inputs, results, equations, assumptions and references, with fields for project, engineer and revision. The full report also includes the charts and interpretations, in color. In the print dialog, choose Save as PDF.
Put each group (machine, shift, supplier) in its own column with the name in the first row, copy the columns and paste them into the values box. Columns may have different lengths. If your data are in a group column and a value column, choose the Stacked layout.
Vertical is the classic layout, good for up to 6 or 8 groups with short names. Horizontal works better with many groups, long names and on phones, because each group gets its own row. Use the Vertical and Horizontal buttons above the chart; the choice also applies to the PNG and the PDFs.
With the Minitab method: Q1, median and Q3 at positions (N + 1)·0.25, (N + 1)·0.5 and (N + 1)·0.75 of the sorted data, interpolating between neighbors. Excel’s QUARTILE.INC uses another rule and may give slightly different Q1 and Q3 with small samples.
A value more than 1.5 × IQR below Q1 or above Q3. The page shows each one with its value and spreadsheet row, so you can go straight to the record. An outlier calls for investigation (measurement error, typing, a part from another lot); only remove it once the cause is found.
The notch shows the 95% confidence interval of the median. When the notches of two groups do not overlap, the difference between the medians is probably real. For a formal conclusion, use the Kruskal-Wallis test or ANOVA with the button below.
A mean (◆) far from the median signals skewness or outliers pulling the value. The points show how much data each box holds and whether there are clusters the box hides; with more than 50 values per group they are hidden in automatic mode.
No. The box plot shows where the differences are and whether the spreads are similar, which is an ANOVA condition. If the boxes look different, confirm with ANOVA (means) or Kruskal-Wallis (medians); if one box is much longer, investigate that group first.
Important notice: Indus Metrics tools produce estimates and pre-sizing results from the data you enter and from published engineering methods. They do not replace design, calculations or reports signed by a licensed professional engineer (PE), nor verification against the applicable codes, standards and regulations, such as OSHA rules and the ASME codes. Material and fuel properties vary: check manufacturer data or your own process analyses before deciding. By using this site you agree to the Terms of Use.
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