This macro displays the frequency of date/time observations that fall into user-specified time intervals. For example, say you have failure times in a column and wish to know how many failures occurred within 15 minute intervals.
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Suppose your raw date/time data are in C1 and you wish to determine how many observations occurred in 15 minute intervals, beginning at 8:00 AM on 1/1/2009 and ending at 4:00 PM of the same day. As well, say you wish to store the intervals in column C3 and the frequencies of observations in those intervals in column C4.To run the macro, chooseand type:
%TIMEINTS C1 "1/1/2009 8:00 AM" "1/1/2009 3:00 PM" 15 C3 C4
Click Submit Commands.
The first argument after the %TIMEINTS command is the column containing the date/time data. The second argument is the starting time of the first interval, enclosed in double-quotes. Use the format used in the date/time data. The third argument is the end time of the last interval, enclosed in double-quotes. The fourth argument is the length of the intervals, in minutes. The fifth argument is the column you wish to store the intervals in and the sixth argument is the column you wish to store the frequencies.
As with Minitab's histogram algorithm, observations that fall on interval boundaries are placed into the interval to the right, with one exception: observations on the boundary of the interval that is farthest to the right are placed in the final interval.