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From |
Ebru Ozturk <ebru_0512@hotmail.com> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
RE: st: 1-4 scale |

Date |
Sat, 4 Aug 2012 21:10:20 +0300 |

Dear David, Thank you. By a factor variable, do you mean factor analysis? as I didnt understand why the model will have three coefficients. ---------------------------------------- > Date: Sat, 4 Aug 2012 08:26:43 -0400 > Subject: Re: st: 1-4 scale > From: dchoaglin@gmail.com > To: statalist@hsphsun2.harvard.edu > > Dear Ebru, > > Your options probably depend on how much data you have. > > In some areas, it is customary to assign the values 1 through 4 to > each question, form the sum of the four questions in each of the two > headings, and use those two variables in your model. Centering is > probably not important at this stage. > > That approach chooses one particular way of combining the four > questions in each heading. To let the data choose the combination, > you can use all eight questions in your model, instead of the two > sums. You should probably check that no two questions are highly > correlated. > > If you have enough data, you can (as Nick suggested) use a factor > variable for each question. Then your model will have three > coefficients for each question. This approach avoids the assumption > that the response categories for a question are equally spaced. > > I would not exclude the possibility of interactions between questions. > In principle, you can cross-classify the data on the eight questions, > but the full cross-classification would have 4^8 = 2^16 cells. For > the separate sets of four questions, the cross-classification would > have 256 cells. > > David Hoaglin > > On Sat, Aug 4, 2012 at 6:24 AM, Ebru Ozturk <ebru_0512@hotmail.com> wrote: > > > > Dear All, > > > > I have a question on how to add a variable that includes items measured by likert scale to the estimation model. > > > > For instance, in the data there is one question that measures the objectives of innovation activities. The answers to the question include 8 items that have been measured by 1-4 scale. I will split them into two headings as they focus on two types of objectives. Thus, for each 4 item how do I add them to the model? Because it is 1-4 scale so do I need to mean centred them or do something else? > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**RE: st: 1-4 scale***From:*Richard Williams <richardwilliams.ndu@gmail.com>

**Re: st: 1-4 scale***From:*David Hoaglin <dchoaglin@gmail.com>

**References**:**st: 1-4 scale***From:*Ebru Ozturk <ebru_0512@hotmail.com>

**Re: st: 1-4 scale***From:*David Hoaglin <dchoaglin@gmail.com>

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