Forum for the observation and analysis of more than one statistical variable at a time. http://forums.stat.ucla.edu/list.php?7 Mon, 23 Nov 2009 22:46:00 -0800 Phorum 5.2.10 http://forums.stat.ucla.edu/read.php?7,151,151#msg-151 http://forums.stat.ucla.edu/read.php?7,151,151#msg-151
They may choose from five Likert-style responses:

'Strongly Disagree'
'Disagree'
'Neutral'
'Strongly Agree'
'Agree'

A colleague suggested dichotomizing the responses - i.e. 'Strongly Disagree' and 'Disagree' combined into '0/no', and 'Strongly Agree' and 'Agree' combined into '1/yes' and then using logistic to regress the response about barriers to diagnosis on risk factors (family history, childhood health issues, and current (adult) health issues).

I am here for a second opinion.

I also am unsure of what to do with the 'Neutral' responses when dichotimizing.

Thank you!]]> bridgette Multivariate Analysis Tue, 17 Nov 2009 10:33:50 -0800 http://forums.stat.ucla.edu/read.php?7,110,110#msg-110 http://forums.stat.ucla.edu/read.php?7,110,110#msg-110
I have 2 types of dependent variables: binary (yes/no) and ordinal (5 likert categories). And 4 types predictors: binary, continuous (age), ordinal (education) and interval (income).

I would like to analyse each outcome against the whole set of predictors, preferable with SPSS. I assume that I have to use Binary Logistic Regression for the binary outcome; and Ordinal Logistic Regression for the ordinal outcome. However, I don't know how to deal with the ordinal & interval predictors in both mentioned methods. All the books i have read only show to use the Logistic Regression with categorial predictor (using dummy variable), without considering the rank/order of the categorial predictor.

Many thanks in advance for your help.]]> meilinda Multivariate Analysis Sat, 03 Oct 2009 06:00:31 -0700 http://forums.stat.ucla.edu/read.php?7,79,79#msg-79 http://forums.stat.ucla.edu/read.php?7,79,79#msg-79 I think that the test I need to perform is a "multi factorial logistic regression"? Is this correct? And anybody know what is the easiest way to perform this test i.e. what software program (online, bought, or otherwise) is best?]]> statnoob Multivariate Analysis Mon, 17 Aug 2009 12:04:06 -0700 http://forums.stat.ucla.edu/read.php?7,65,65#msg-65 http://forums.stat.ucla.edu/read.php?7,65,65#msg-65
The Training dataset is about 2500 cases and 6500 controls. 700 variables were selected comparing case vs control group at p<0.001.
The independent dataset for validating the result is 500 cases and 500 controls.
So I use Logistic Regression on the training dataset, and selected 350 predicting variables (out from the 700 significant variables) using stepwise selection, cut-off at p=0.05

Now I'd like to apply these 350 variables on the 500 case/500 control dataset; and see how good it can do the prediction of an individual being a patient. But it is small and 350 variables will be overfitting using Logistic Regression. I still apply Logistic Regression to do stepwise selection, using p=0.05 (35 variables were selected) and p=0.10 (60 variables were selected), p=0.15 (76 variables were selected) and p=0.20 (118 variables were selected); the Hosmer & Lemeshow Goodness of fit for all four selections, p>0.05.

I'm not sure if this is a good approach, or do you have any suggestion in terms of how to use the independent dataset to do validation from the 350 variables selected from the training dataset? Thank you very much.]]> HuiW Multivariate Analysis Wed, 22 Jul 2009 12:53:42 -0700 http://forums.stat.ucla.edu/read.php?7,23,23#msg-23 http://forums.stat.ucla.edu/read.php?7,23,23#msg-23 questionboy Multivariate Analysis Thu, 02 Apr 2009 22:17:54 -0700 http://forums.stat.ucla.edu/read.php?7,22,22#msg-22 http://forums.stat.ucla.edu/read.php?7,22,22#msg-22 questionboy Multivariate Analysis Thu, 02 Apr 2009 21:27:44 -0700 http://forums.stat.ucla.edu/read.php?7,4,4#msg-4 http://forums.stat.ucla.edu/read.php?7,4,4#msg-4 Jose Hales-Garcia Multivariate Analysis Mon, 02 Mar 2009 12:06:54 -0800