Freedman–Diaconis rule

Freedman–Diaconis rule is a non-parametric method used to determine the optimal number of bins in a histogram, which is crucial for accurately representing the distribution of a dataset. This rule is particularly useful in statistics and data analysis, providing a way to visually interpret the underlying distribution of data without making any assumptions about its shape. The rule is named after the statisticians David A. Freedman and Persi Diaconis.

Overview

The Freedman–Diaconis rule is based on the interquartile range (IQR) and the number of data points (N) in a dataset. The IQR is a measure of statistical dispersion and is the difference between the 75th and 25th percentiles of the data. This rule is designed to minimize the difference between the empirical distribution function and the underlying probability distribution of the data.

The formula for determining the bin width (h) is given by:

\[ h = 2 \times \left(\frac{IQR}{N^{1/3}}\right) \]

Once the bin width is calculated, the number of bins (k) can be determined by dividing the range of the data by the bin width:

\[ k = \left\lceil \frac{\text{max(data)} - \text{min(data)}}{h} \right\rceil \]

Application

The Freedman–Diaconis rule is widely used in various fields such as medicine, engineering, and economics to analyze and interpret data. It is particularly beneficial when dealing with large datasets or when the distribution of the data is unknown.

Advantages and Limitations

One of the main advantages of the Freedman–Diaconis rule is its non-parametric nature, meaning it does not assume a normal distribution of the data. However, its reliance on the IQR can make it less sensitive to outliers compared to other methods. Additionally, in cases of multimodal distributions, the rule may not provide the most accurate representation.

Related Pages

• Histogram
• Interquartile range
• Statistical dispersion
• Data analysis

See Also

• Sturges' rule
• Scott's rule
• Histogram binning