This is machine translation

Translated by Microsoft
Mouseover text to see original. Click the button below to return to the English verison of the page.

Note: This page has been translated by MathWorks. Please click here
To view all translated materals including this page, select Japan from the country navigator on the bottom of this page.

Fit Distributions to Grouped Data Using ksdensity

This example shows how to fit kernel distributions to grouped sample data using the ksdensity function.

Step 1. Load sample data.

Load the sample data.

load carsmall;

The data contains miles per gallon (MPG) measurements for different makes and models of cars, grouped by country of origin (Origin), model year (Model_Year), and other vehicle characteristics.

Step 2. Group sample data by origin.

Group the MPG data by origin (Origin) for cars made in the USA, Japan, and Germany.

Origin = nominal(Origin);
MPG_USA = MPG(Origin=='USA');
MPG_Japan = MPG(Origin=='Japan');
MPG_Germany = MPG(Origin=='Germany');

Step 3. Compute and plot the pdf.

Compute and plot the pdf for each group.

[fi,xi] = ksdensity(MPG_USA);
hold on

[fj,xj] = ksdensity(MPG_Japan);

[fk,xk] = ksdensity(MPG_Germany);

title('MPG by Origin')
hold off

The plot shows how miles per gallon (MPG) performance differs by country of origin (Origin). Using this data, the USA has the widest distribution, and its peak is at the lowest MPG value of the three origins. Japan has the most regular distribution with a slightly heavier left tail, and its peak is at the highest MPG value of the three origins. The peak for Germany is between the USA and Japan, and the second bump near 44 miles per gallon suggests that there might be multiple modes in the data.

See Also

Related Examples

More About

Was this topic helpful?