Univariate Analysis

Single Band

"Empirical" Method

The "empirical" peak determination method assumes that the specified region should include a peak with a maximum near the center of the specified region. A local, linear baseline is drawn from the minimum values within the "search window" from the edges of the region. This baseline is subtracted from the region, then the maximum, peak center (abscissa value of maximum), area, and an estimate of the full-width at half-maximum are calculated. The baselines are also calculated by drawing a line from the inflection points (determined by the points where the 1st derivative crosses the origin).

"Region Statistics" Method

The region statistics method assumes nothing about the specified region and simply calculates basic statistics (area, maximum, maximum position, mean, median, minimum, minimum position and standard deviation).

Band Ratio

The band ratio method allows you to perform univariate analysis on two different peak regions and calculate the ratio of one region to another.

Concatenating Univariate Results

You may want to perform multivariate analysis on univariate results for multiple peak regions. You can do this by concatenating multiple univariate analysis results together. For each metric, the columns will be in alphabetical order of the selected univariate results names.

Calculated Metrics

Metric	Description
Adjusted Area	The trapezoidal sums of the specified region between the inflection points (minima of the first derivative) after substraction of the local baseline
Adjusted Area Between Inflection Points	The trapezoidal sums of the specified region after subtraction of the local baseline
Adjusted Peak Intensities	The local maxima of the specified region after subtraction of the local baseline
Area Between Inflection Points	The trapezoidal sums of the spectra between the inflection points (minima of the first derivative).
Empirical FWHM	The distance in abscissa units between the points located nearest to one half the distance between the local baseline and the local maximum
Peak Centers	The abscissa value of the local maxima the specified region
Peak Intensities	The local maxima the specified region
Total Area	The trapezoidal sums of the specified region

"Under the Hood"

Univariate analysis is implemented in in quantification.cpp. The "empirical" method is implemented in Vespucci::Math::Quantification::QuantifyPeakMat, the "region statistics" method is implemented in Vespucci::Math::Quantification::PeakStatistics