[Eeglablist] How to Interpret Insignificant Coefficients of Regression Analysis

[Iman Mohammad-Rezazadeh]

Joaquin ,

The set of parameters which I have is stimulus parameter for tDCS (Current, PW, and some categorical variables). At the first level, I am planning to run a logistic regression model just to see if these parameters would cause an impact ( measured by our method) or not. Then I will be using a stepwise GLM to model the actual level of output.

For the logistic model since the output is nominal ( TURE/FALSE), I cannot use the stepwise method.

any suggestions?

-Iman


________________________________
From: Joaquin Rapela <rapela at ucsd.edu>
Sent: Wednesday, June 14, 2017 2:25 PM
To: Iman Mohammad-Rezazadeh
Cc: EEGLAB List; Anthony Zanesco
Subject: Re: [Eeglablist] How to Interpret Insignificant Coefficients of Regression Analysis

Dear Irman,

The answer to your question depends on what you want to learn from the
regression model.

a. If I were interested in learning how a set of independent measures affect a
dependent one, I would report both significant and insignificant coefficients.
In this way the reader of my article would know the impact (and lack of impact)
of each of the independent variables.

b. If I ware interested in knowing what is the best model for my dependent
variable, I would start with a model with a large number of independent
variables,  and their interactions, use some model selection criterion (e.g.,
stepwise model selection with the Akaike information criterion), and only
report the variables of the selected model.

Cordially, Joaquin

On Wed, Jun 14, 2017 at 06:10:28PM +0000, Iman Mohammad-Rezazadeh wrote:
>    Hi EEGLABers,
>
>    This question is for mostly stats guru:
>
>    If we develop a regression model (logistic, GLM, ...) and some of the
>    coefficient of the for the model is insignificant then how would
>    someone interpret that coefficient? should we through them away or
>    still keep them in the model? Should we consider their effect size as
>    the key parameter ?
>
>    Thank you,
>
>    Iman

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--
Joaquin Rapela, PhD
Swartz Center for Computational Neuroscience
University of California San Diego
9500 Gilman Drive,
San Diego, CA 92093-0559
tel: (858) 822-7547
fax: (858) 822-7556
http://sccn.ucsd.edu/~rapela/
----------------------------------

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                                                         Hamlet, Act 3, Scene 4
                                                         William Shakespeare
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