| Author |
 Topic  |
|
|
zaza_DG
USA
2 Posts |
 Posted - 10/02/2005 : 5:27:54 PM
|
Hi folks,
I am trying to fit distribution of rise time of synaptic currents (mIPSCs). I import single column of rise times in Origin spread sheet and perform frequency distribution, which yields X and Y columns. I build bar graph from these columns and then press quote:
FIT MULTIPLE GAUSSAN
. I am having difficulty to figure out how many peaks I need to choose. In most recordings it can be analyzed with either 2 or 3 peaks. How do you judge how many peaks you have? In a separate question, do you use the value initial half wide estimate that is already there, or you enter it manually?. And finally, what does w1, w2 etc. mean? I guess xc means peak of each gaussian. What is difference between no weighting and weighting? Many thanks for your time
|
|
|
easwar
USA
1964 Posts |
Posted - 10/03/2005 : 1:36:00 PM
|
Hi,
quote:
I am having difficulty to figure out how many peaks I need to choose. In most recordings it can be analyzed with either 2 or 3 peaks. How do you judge how many peaks you have?
You will need to use some criterion to decide how many peaks to fit with. If the peaks are not clearly visible in the data, you may need to use some other technique to locate where they are (such as they could be hidden in the shoulder of another peak etc). We have a Peak Fitting Module that may be more appropriate for such fitting.
quote:
In a separate question, do you use the value initial half wide estimate that is already there, or you enter it manually?.
The estimate that Origin comes up with should be fine. The iterative procedure will freely vary width for each peak and it should converge to optimal value for each peak. This of course depends on the data and how clearly separated the peaks are etc.
quote:
And finally, what does w1, w2 etc. mean? I guess xc means peak of each gaussian.
w1, w2 are width parameter of the gaussian. In the Origin gaussian function, w corresponds to 2 * sigma
quote:
What is difference between no weighting and weighting?
Weighting is typically used when you have error associated with the data/measurement. In order to utilize weighting, you will need to use the NLSF tool or the PFM
Easwar
OriginLab
[/quote]
|
 |
|
| |
Topic |
|
|
|
Help needed in multiple gaussian fit (IPSCs)