PlotNerd

What are quartiles?

Quartiles are values that divide sorted data into four equal parts. Q1 is the first quartile (25th percentile), Q2 is the median (50th percentile), and Q3 is the third quartile (75th percentile). They're essential for understanding data distribution in statistical analysis.

What is a 5 number summary?

A 5 number summary includes the minimum value, first quartile (Q1), median (Q2), third quartile (Q3), and maximum value. These five key statistics completely describe the distribution characteristics of a dataset and form the basis for box plot visualization.

Is my data safe with PlotNerd?

PlotNerd uses 100% client-side computing, meaning all your data is processed only in your browser and never sent to servers or third parties. It works even offline, ensuring complete data security and privacy protection.

What algorithms does PlotNerd support?

PlotNerd supports 5 major quartile calculation algorithms: Tukey Hinges (textbook method), R/Python Standard (R-7 / Type 7), Excel QUARTILE.INC (Type 7), Excel QUARTILE.EXC (Type 6), and a WolframAlpha-compatible method (R-5). This ensures compatibility with major statistical software and spreadsheet workflows.

Can I compare multiple data groups in one box plot?

Yes! PlotNerd supports multi-series grouped box plots. Use Series Mode and enter data in the format 'Group Name: value1, value2, value3' per line. This allows you to compare multiple groups (e.g., different classes, experiment groups) side-by-side on the same chart for easy visual comparison.

What is MAD outlier detection and when should I use it?

MAD (Median Absolute Deviation) is a robust outlier detection method that works better than Tukey's 1.5×IQR rule for skewed data. Use MAD when your data distribution is asymmetric or contains many outliers. PlotNerd allows you to switch between Tukey and MAD methods to see how outlier detection differs.

What are notched box plots and what do they show?

Notched box plots display a confidence interval around the median (the notch). If the notches of two groups don't overlap, it suggests their medians are statistically significantly different. This is useful for comparing multiple groups and determining if differences are meaningful or just due to chance.

How to calculate interquartile range (IQR)?

The interquartile range (IQR) is calculated as Q3 - Q1, representing the spread of the middle 50% of your data. PlotNerd automatically calculates IQR for all supported algorithms and provides instant verification with WolframAlpha.