Teledyne LeCroy SAS Suite User Manual - Manual (Page 280)

Version 6.25 SASSuite User Manual
270
LeCroy Corporation
Copy this formula down the length of the column, and all original text data is converted
to numeric data expressed in microseconds.
Note: If the data fields contain other units such as seconds or nanseconds,
the formula will need to be modified to account for all units used.
The commands in the file can now be sorted in increasing or decreasing order of
command completion time by selecting all rows containing data, then selecting Sort from
the Data menu in Microsoft Excel. Choose the column which contains the numeric
completion times, and select "Ascending" or "Descending".
Creating a
Histogram
using
Microsoft
Excel
Microsoft Excel and other database and spreadsheet programs often have sophisticated
statistical functions useful for analyzing the data produced by SASTracker. For example,
it may be useful to have a histogram of command completion times for a Command Log
File, to show the range and the pattern of variation of the command completion times. A
histogram is a chart which shows the frequency of occurance of values within a specified
data range, and allows the user to easily see which completion times cluster around
certain values, and which are unusual.
One way to create this chart is to begin by converting all command completion times into
data values as described above. Once this column is created, some basic statistic values
can be determined using Excel formulas, such as the following (in this example, the data
is contained in column Q, rows 2 through 512):
•
The number of valid datapoints can be determined by using the formula "=511
- COUNTBLANK(Q2:Q512)"
•
The maximum value in the range of command completion times can be
determined by the formula "=MAX(Q2:Q512)"
•
The minimum value in the range of command completion times can be
determined by the formula "=MIN(Q2:Q512)
Once the minimum and maximum values are known, the histogram can be prepared by
deciding on the "buckets" to be used to collect the data.
An example is shown below. In this example, the measured command completion times
varied from 1.645 microseconds to 36,852 microseconds. Data "buckets" were set up for
the following ranges:
•
Less than 2 us
•
2-3 us
•
3-5 us
•
5-10 us
•
10-100 us
•
100-1,000 us
•
1,000-10,000 us
•
10,000-50,000 us
These values were entered in cells Q519 through Q526.
To create the histogram, first select all cells which will contain the data, in this case cells
R519 through R526. Type in the following formula:
=FREQUENCY(Q2:Q512,Q519:Q526)