sparsity: A function to calculate the sparsity of the variable
Description
When two or more variables are merged together, it is
very likely that spurious sparsity is created. This is
due to the fact that the years between the variables are
not identicle and is particularly true for data stored as
data.frame with country and year as column indexes.
Usage
sparsity(year, var, data)
Arguments
year
The column which index the time
var
The variable to calculate sparsity
data
The data frame.
Details
This function computes the sparsity by taking the data
which are observed between the first and the last
observation.
For example, if variable A is observed since 1960 while
variable B is collected since 1990. When they are merged
together, NA's will be created for variable prior to 1990
and these should not be used to calculate the sparsity of
the data.