# Sensitivity Analysis: Standard Regression Coefficients

**URL:** <https://uqworld.org/t/sensitivity-analysis-standard-regression-coefficients/742>\
**Category:** Community Q&A and How To\
**Tags:** sensitivity\
**Created:** [July 10, 2020, 7:25pm UTC](https://uqworld.org/t/sensitivity-analysis-standard-regression-coefficients/742 "2020-07-10T19:25:15Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![AHz](https://uqworld.org/user_avatar/uqworld.org/ahz/32/471_2.png) [@AHz](https://uqworld.org/u/AHz)\
**Post date:** [July 10, 2020, 7:25pm UTC](https://uqworld.org/t/sensitivity-analysis-standard-regression-coefficients/742/1 "2020-07-10T19:25:15Z")

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Dear All,

I am trying to run SRC from sample-based sensitivity analysis. I’ve got 1000 inputs and 200 outputs, and the sample size is 10000. I intend to measure how much the dependant variable varies to the variance of the independent inputs uncertainties.

I receive the following error:

> Error in uq\_SRC\_indices (line 88)  
> totSRCIdx((Options.FactorIndex)) = SRCIdx;

Could you please inform me why such error has occurred, what it means, and how I could solve the problem?

Thanks 🙂

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**Author:** ![nluethen](https://uqworld.org/user_avatar/uqworld.org/nluethen/32/218_2.png) [@nluethen](https://uqworld.org/u/nluethen)\
**Post date:** [July 14, 2020, 8:52am UTC](https://uqworld.org/t/sensitivity-analysis-standard-regression-coefficients/742/2 "2020-07-14T08:52:56Z")

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Hi @AHz,

SRC is simple linear regression of the output Y onto the input variables X\_i. Given that you have 10000 samples for 1000 inputs, this should in principle not be a problem. Without more information about the error message or your data (or your Matlab code) I’m afraid I cannot tell you much more. Did you use the option `SensOpts.FactorIndex` (see [Sensitivity Analysis user manual](https://uqftp.ethz.ch/uqlab_doc_pdf/1.3.0/UserManual_Sensitivity.pdf), section 2.4.1)? For which of the 200 outputs do you receive this error?

May I ask why you have 200 outputs? Is it maybe a time series or a displacement field? It might be advantageous to do some dimension reduction (see e.g. @xujia’s [post](https://uqworld.org/t/structural-reliability-and-building-collapse-in-uqlab/714/2) mentioning the use of PCA or patterns in the data) before you do the sensitivity analysis.

Also, 1000 inputs seem like a lot. Are these really all independent variables, in whose influence on the output you are interested? Could you maybe do some dimension reduction to a few meaningful variables?

The question is whether a result in the form of “Variable 257 has the most influence on output #2, whereas variable 903 has the most influence on outputs #178 and #191” is meaningful and interpretable to you. (And note that SRC only looks for linear dependence!)

I hope this helps, let us know how you proceed! 🙂

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**Author:** ![damarginal](https://uqworld.org/user_avatar/uqworld.org/damarginal/32/73_2.png) [@damarginal](https://uqworld.org/u/damarginal)\
**Post date:** [December 4, 2020, 3:36pm UTC](https://uqworld.org/t/sensitivity-analysis-standard-regression-coefficients/742/3 "2020-12-04T15:36:49Z")

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