Opened 12 years ago
Closed 12 years ago
#305 closed bug (fixed)
Large standard deviation values from linear fits?
Reported by: | cwelch@… | Owned by: | srkline |
---|---|---|---|
Priority: | major | Milestone: | Release 7.0 Maintenance |
Component: | Analysis | Keywords: | |
Cc: | Blocking: | ||
Task: |
Description
When I use the linear fits package in v. 7.03, I get very large standard deviation values. For example, when doing a Guinier plot to obtain Rg, I might get Rg = 44.142 +/- 5880 Angstroms. For this same example, the Chi-Squared value was 8.8941e-09. With previous versions of the NCNR Igor macros, I did not encounter such problems. Is this a known issue, or have I inadvertently set some parameter to the wrong value or done something else wrong? I do not encounter similar problems when using the Curve Fit features.
Change History (1)
comment:1 in reply to: ↑ description Changed 12 years ago by srkline
- Milestone set to Release 7.0 Maintenance
- Resolution set to fixed
- Status changed from new to closed
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The /I=1 flag should be I=0, since the weights are calculated as 1/err -- since this procedure was written way back in time when that was the only acceptable way for the weights to be cast. fixed in r746