BSL PRO 4 Manual - Biopac

92 BSL PRO ManualKurtosisLin_regMaxMax TMinimum area:2 samplesUses:All points ofselected areaMinimum area:1 sampleUses:All points ofselected areaMinimum area:1 sampleUses:All points ofselected areaKurtosis indicates the degree of peakedness in a distribution, e.g. the size of the“tails” of the distribution. Distributions that have sharp peaks in their center havepositive kurtosis; flatter distributions have negative kurtosis. A normal distributionhas a kurtosis of 0. The following formula is used to extract kurtosiskurtosis i1nni1nnx xix xWhere from a signal (x) containing n points:Linear regression is a better method to calculate the slope when you have noisy,erratic data.Lin_reg computes the non-standard regression coefficient, which describes theunit change in f (x) (vertical axis values) per unit change in x (horizontal axis).For the selected area, Lin_reg computes the linear regression of the line drawnas a best fit for all selected data points using the following formula:nnnLin_reg =n i242x f x x f xn n2 x i x ii1 i1i iii1 i1 i1n2Where:n—number of samples;i—index (i = 1.n);xi — values of points at horizontal axis ( x1– the first point, xn– the last point);f x i- values of points of a curve ( vertical axis).Note: For a single point, Lin_reg computes the linear regression of the line drawnbetween the two samples on either side of the cursor.Results:If the data value at the starting location is greater than the data value at theending location of the cursor, then a negative delta will result. Otherwise, apositive delta will result.Units: Volts/sec.This value is normally expressed in unit change per second (time rather thensamples points) since high sampling rates can artificially deflate the value of theslope. If the horizontal axis is set to display Frequency or Arbitrary units, the slopewill be expressed as unit change in corresponding vertical axis values (frequencyor arbitrary units, respectively).Sample data file:“ValidateMeasurements.ACQ”Result: 230.00 Volts/sec. (for 1-4 samples) and–170.00 Volts/sec. (for samples 4-7).Max (maximum) shows the maximum amplitude value of the data samplesbetween the endpoints of the selected area. To compare peak heights, selecteach peak—you can easily see the maximum peak values or paste the results tothe journal. Also, since you can simultaneously obtain measurements for differentchannels, you can easily compare maximum values for different channels.Note: For a single point, Max shows the amplitude value in this point.Units: VoltsMax T shows the time of the data point that represents the maximum value of thedata samples between the endpoints of the selected area.Note: For a single point, Max T shows the time value in this point.Units: SecondsiVisit the online support center at www.biopac.com