Graphics Programs Reference
In-Depth Information
var(corg)
ans =
1.3595
The standard deviation is the square root of the variance.
std(corg)
ans =
1.1660
It is important to note that by default the functions
var
and
std
calculate the
sample variance and standard deviation representing an unbiased estimate of
the sample dispersion of the population. While using
skewness
to describe
the shape of the distribution, we observe a negative skew close to zero:
skewness(corg)
ans =
-0.2529
Finally, the peakedness of the distribution is described by the kurtosis. The
result from the function
kurtosis
,
kurtosis(corg)
ans =
2.4670
suggests that our distribution is slightly fl atter than a gaussian distribution
since its kurtosis is lower than three. Most of these functions have cor-
responding versions for data sets containing gaps, such as
nanmean
and
nanstd
, which treat
NaN
·s as missing values. To illustrate the use of these
functions we introduce a gap to our data set and compute the mean using
mean
and
nanmean
for comparison.
corg(25,1) = NaN;
mean(corg)
ans =
NaN
nanmean(corg)
ans =
12.3371
In this example the function
mean
follows the rule that all operations with
