Thermonicolet Omnic Software User's Guide 6.1 (PDF) - Charles E ...

3. Choose Average from the Process menu.
The Average dialog box shows the average Y value of the displayed or
selected spectral region.
4. Choose OK.
Performing
statistical
calculations
on spectra
Statistical Spectra in the Analyze menu lets you perform statistical calculations on
two or more selected spectra. For each data point (X value), you can find the
average, variance and range of Y values for the spectra, as described in the table
below.
Calculation
Description
Average
The arithmetic mean of the Y values for each data point. (The Y
values for a data point are added together, and then the total is
divided by the number of spectra.)
Possible uses: By calculating and saving the average of a group of
spectra (of samples from a production run, for example), you can
“average out” sample preparation and sampling variations. You
can also use the average obtained from a group of standard
samples as a reference (added to a search or QC library) that may
be more representative of a compound than any single spectrum.
Variance
The standard deviation of the Y values for each data point. (The
mathematical formula for standard deviation is used.)
Possible uses: By comparing the variance of different peaks, you
can detect the introduction of impurities in a production process.
You can also calculate the variance of spectra of a standard sample
collected at different times to check the repeatability of the
spectrometer’s measurements.
Range
The range of Y values for each data point. (The lowest Y value for
a data point is subtracted from the highest Y value for that point.)
Possible uses: By comparing the ranges of groups of samples from
different production runs, you can detect changes in how
controlled a production process is. You can also compare the
ranges obtained for a group of standard samples collected at
different times to check the repeatability of the spectrometer’s
measurements.
240 Thermo Nicolet