Re: Help with Dissertation SPSS

Posted by Bruce Weaver on Aug 12, 2011; 7:25pm
URL: http://spssx-discussion.165.s1.nabble.com/Help-with-Dissertation-SPSS-tp4693273p4694460.html

Hi Sonia.  The "days" variable is:  1 = no days, 2 = 1-5 days, 3 = 6-10 days, 4 = 11-20 days, 5 = more than 20 days.  I would describe that as ordered categories, not nominal.  But in either case, categorical variable like this certainly can be used in regression models, but one has to compute k-1 indicator variables to do so (where k = the number of categories).  A DO-REPEAT is a nice way to do that.  E.g.,

do repeat f = f1 to f5 / # = 1 to 5.
- compute f = (days EQ #).
end repeat.

Then use 4 of the 5 f-variables to code for frequency of play.  The omitted 5th f-variable will be the reference category for the t-tests you see in the table of regression coefficients.  Using 4 of the 5 indicators for "days" this way in REGRESSION gives exactly the same result you get by treating the original "days" variable (with 5 categories) as a fixed factor with UNIANOVA.  (Make up an example and give it a try.)

p.s. - I'll save Jon the trouble of adding that there is a Python-based method for computing indicator variables too.  Most of the people I know locally do not have Python installed, however, and I'll bet many of them have never even heard of it.  So I like sticking to native SPSS code when possible.  ;-)

HTH.

Sonia Brandon-2 wrote

Your IV regarding the number of days is most definitely nominal, so you shouldn't use regression, especially on something for a dissertation.  If you had asked for the actual number of days, it would be ratio, and then regression would be more appropriate.  On your DVs, what are the response values?  Is it a true scale or a Likert scale - or is it yes/no response?  Just guessing, it sounds like you may have multiple interval DVs, and with Categorical IVs (type of game and frequency category), you may want to take a look at MANOVA as the appropriate technique.
 
 
 
 
Sonia Brandon, Ph.D.
Director, Institutional Research
Colorado Mesa University
1100 North Avenue
Grand Junction, CO  81501
phone: [phone]
fax:  [phone]
email: [hidden email]
>>> Garry Gelade <[hidden email]> 8/12/2011 11:46 AM >>>
How many subjects do you have? And what is/are your research questions? Eg
Frequency of playing any type of game affects aggressive & prosocial
behaviours? Or Frequency of playing violent games affects these behaviours?
Or both?

Sticking with the regression for the moment, if I have understood your data,
in the first case, your IV could be the total frequency score for all games.
In the second case you could total the frequency ratings for each type of
game, giving you 3 IVs.


Garry


-----Original Message-----
From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of
Muralli
Sent: 12 August 2011 14:17
To: [hidden email]
Subject: Help with Dissertation SPSS

My study is the effects of video games on prosocial behavior.

2 DV = prosocial behavior and aggression - measured with a 38 item
questionnaire (15 Aggressive/23 Prosocial)
IV = I used a video game questionnaire where participants are asked to rate
the frequency of gameplay they have had in the past month (1 = no days, 2 =
1-5 days, 3 = 6-10 days, 4 = 11-20 days, 5 = more than 20 days). This is
done for 8 games (RPG, adventure, strategy, platform, action and fight,
first person shooter, sports, racers). These games are divided into 3
groups, violent, non-violent and neutral.

I tried to do a multiple regression since someone told me that my IVs are
not categorical but continuous. I compiled the scores for my DV and computed
with target variable splitting up the aggressive questions and the prosocial
questions (Q1 + Q3 + Q5, etc). Thus, the score comes up to 80, 103, 76 etc.

Then I used each game as an IV but since they only had to rate the
frequency, the data for each IV was 6, 3, 5, etc.

Clearly, this led to a non-significant result and then I understood why.

I have to idea how to use my IV and i'm not sure what test to use, I hope
the way I have totaled my DVs were right.

The proposed method which was approved was using a One-way between subjects
ANOVA with 1 DV (Prosocial) and 1 IV Video games (Violent, non-violent,
neutral).

I don't see how to do this because the prosocial survey measures two things
as mentioned earlier and the video games survey is not categorical. At least
that's what i understand from it

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