Multichannel Systems NeuroExplorer - Manual (Page 52)

2.7. Cumulative Sum Graphs
Here is the algorithm that is used to draw optional cumulative sum graphs above the histograms.
Suppose we have a histogram with bin counts bc[i], i=1,...,N. Cumulative Sum Graph displays the
following values cs[i]:
for bin 1: cs[1] = bc[1] - A
for bin 2: cs[2] = bc[1]+bc[2] - A*2
for bin 3: cs[3] = bc[1]+bc[2]+bc[3] - A*3, etc.
The value of A depends on the selected Cumulative Sum option:
A equals to average of all bc[i] if you select "Use all histogram" option
A equals to average of all bc[i] for bins that are before zero on time scale if you select "Use preref as
base" option.
If you use "Use all histogram" option, the value of the cumulative sum for the last bin is always zero:
sc[N] = bc[1]+bc[2]+...bc[N] - A*N, where A = (bc[1]+bc[2]+...bc[N])/N.
NeuroExplorer displays 99% confidence limits for Cumulative Sum Graphs. Confidence limits for "Use
preref as base" option are proportional to square root of bin number.
Calculations of confidence limits for "Use all histogram" option are not trivial. These calculations are
based on the formulas developed by the author of NeuroExplorer, Alexander Kirillov.
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