Mathematics

Removing Outliers

You can remove outliers or misplaced data points from a data set in much the same manner as NaNs. For the vehicle traffic count data, the mean and standard deviations of each column of the data are

mu = mean(count)
sigma = std(count)

mu =
       32.0000   46.5417   65.5833

sigma =
       25.3703   41.4057   68.0281

The number of rows with outliers greater than three standard deviations is obtained with

[n,p] = size(count)
outliers = abs(count - mu(ones(n, 1),:)) > 3*sigma(ones(n, 1),:);
nout = sum(outliers)
nout =
       1    0    0

There is one outlier in the first column. Remove this entire observation with

count(any(outliers'),:) = [];

Data Preprocessing

Regression and Curve Fitting