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From |
Richard Williams <richardwilliams.ndu@gmail.com> |

To |
statalist@hsphsun2.harvard.edu, statalist@hsphsun2.harvard.edu |

Subject |
Re: st: 1-4 scale |

Date |
Sun, 05 Aug 2012 12:52:00 -0500 |

At 10:57 AM 8/5/2012, David Hoaglin wrote:

Dear Ebru, People often analyze data from Likert scales as equally spaced, so you can use each of the eight items in your model as a numerical variable, with values 1 to 4. You simply need to be aware that you are treating the four categories as equally spaced.

It is a debatable practice though. Consider the following (warm has 4 values): use "http://www.indiana.edu/~jslsoc/stata/spex_data/ordwarm2.dta";, clear reg warm yr89 male white age ed prst rvfplot

Earlier you asked about centering those variables. Centering will do no harm. As far as the model is concerned, it affects only the definition of the intercept. If you do decide to "center" the variables, you may want to use one of the four values. If the data on an item are not concentrated at one end, you could use 2 or 3 or perhaps 2.5 as the centering constant. (In a 5-point Likert scale with a neutral category at 3, using 3 would often be a reasonable choice.) When you have the results from the model with the eight separate items, you may want to see whether the coefficients for the four items within a heading are similar. If they are, and it makes sense, you could consider replacing those four items with their sum (or average) --- a composite score. David Hoaglin On Sun, Aug 5, 2012 at 2:35 AM, Ebru Ozturk <ebru_0512@hotmail.com> wrote: > Dear David, >> I use tobit estimation. If I enter each item (8) in the question(objectives of innovation) into the model without changing theirvalues, leaving them as they are (1 to 4), does it work? Becausesometimes tobit can create problems if it has many variables in the model.* * 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/

------------------------------------------- Richard Williams, Notre Dame Dept of Sociology OFFICE: (574)631-6668, (574)631-6463 HOME: (574)289-5227 EMAIL: Richard.A.Williams.5@ND.Edu WWW: http://www.nd.edu/~rwilliam * * 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:*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>

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

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

**RE: 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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