# interpreting t-test results

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## interpreting t-test results

 I have set of results for two different tests taken by the same subjects. I am using the paired sample t-test in SPSS, I assume that is the right one. I get a significant difference between the two  test, both are psychological measures, but I would like to know which test gives me the higher score i.e which psychological construct is most prevalent in my sample, the test scores are calculated differently one ranges from 1- 4 and the other from 24-120. Would I use another analysis to get this answer? ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD
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## Re: interpreting t-test results

 At 07:57 PM 4/5/2009, Talino Bruno wrote: >I have set of results for two different tests taken by the same >subjects. I am using the paired sample t-test in SPSS, I assume that >is the right one. I get a significant difference between the >two  test, both are psychological measures, but I would like to know >which test gives me the higher score i.e which psychological >construct is most prevalent in my sample, the test scores are >calculated differently one ranges from 1- 4 and the other from >24-120. Would I use another analysis to get this answer? The paired t-test tells you whether the score consistently increases or decreases from the first test to the second. If the scores on the first test are 4 or less, and those on the second are 24 or more, then the numerical change from the first to the second is always positive. The t-test will show a clearly significant result, but that's an artifact; it's meaningless. You can't test for a significant difference, or even define what it is, unless the two quantities are measured on the same scale. ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD
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## Re: interpreting t-test results

 In reply to this post by Talino Bruno Talino, You would need to compare scales that are based on the same metric in order to have a meaningful result. The numbers for the second scale may be higher because the rating scale uses larger numbers, but that does not imply that levels of some construct are higher. HTH, Steve Brand www.StatisticsDoc.com -----Original Message----- From: SPSSX(r) Discussion [mailto:[hidden email]]On Behalf Of Talino Bruno Sent: Sunday, April 05, 2009 7:58 PM To: [hidden email] Subject: interpreting t-test results I have set of results for two different tests taken by the same subjects. I am using the paired sample t-test in SPSS, I assume that is the right one. I get a significant difference between the two  test, both are psychological measures, but I would like to know which test gives me the higher score i.e which psychological construct is most prevalent in my sample, the test scores are calculated differently one ranges from 1- 4 and the other from 24-120. Would I use another analysis to get this answer? ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD
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## Re: interpreting t-test results

 So the question is if it's only the coding which is different or if it's two completely different measures. Can you, in other words, recode one scale into the other before the t-test? Best, Henrik Quoting Statisticsdoc <[hidden email]>: > Talino, > > You would need to compare scales that are based on the same metric in order > to have a meaningful result. The numbers for the second scale may be higher > because the rating scale uses larger numbers, but that does not imply that > levels of some construct are higher. > > HTH, > > Steve Brand > > www.StatisticsDoc.com > > -----Original Message----- > From: SPSSX(r) Discussion [mailto:[hidden email]]On Behalf Of > Talino Bruno > Sent: Sunday, April 05, 2009 7:58 PM > To: [hidden email] > Subject: interpreting t-test results > > > I have set of results for two different tests taken by the same subjects. I > am using the paired sample t-test in SPSS, I assume that is the right one. > I get a significant difference between the two  test, both are > psychological measures, but I would like to know which test gives me the > higher score i.e which psychological construct is most prevalent in my > sample, the test scores are calculated differently one ranges from 1- 4 and > the other from 24-120. Would I use another analysis to get this answer? > > ===================== > To manage your subscription to SPSSX-L, send a message to > [hidden email] (not to SPSSX-L), with no body text except the > command. To leave the list, send the command > SIGNOFF SPSSX-L > For a list of commands to manage subscriptions, send the command > INFO REFCARD > > ===================== > To manage your subscription to SPSSX-L, send a message to > [hidden email] (not to SPSSX-L), with no body text except the > command. To leave the list, send the command > SIGNOFF SPSSX-L > For a list of commands to manage subscriptions, send the command > INFO REFCARD > ************************************************************ Henrik Lolle Department of Economics, Politics and Public Administration Aalborg University Fibigerstraede 1 9200 Aalborg Phone: (+45) 99 40 81 84 ************************************************************ ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD
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## Re: interpreting t-test results

In reply to this post by Talino Bruno
 Talino, If you compare ant and elephant, the result is always significant.  Ant is always smaller than elephant.  Your case is analogous to the ant-elephant example.  What do you think?   Jims.  --- On Sun, 5/4/09, Talino Bruno <[hidden email]> wrote: From: Talino Bruno <[hidden email]>Subject: interpreting t-test resultsTo: [hidden email]Received: Sunday, 5 April, 2009, 11:57 PM I have set of results for two different tests taken by the same subjects. Iam using the paired sample t-test in SPSS, I assume that is the right one.I get a significant difference between the two  test, both arepsychological measures, but I would like to know which test gives me thehigher score i.e which psychological construct is most prevalent in mysample, the test scores are calculated differently one ranges from 1- 4 andthe other from 24-120. Would I use another analysis to get this answer?=====================To manage your subscription to SPSSX-L, send a message toLISTSERV@... (not to SPSSX-L), with no body text except thecommand. To leave the list, send the commandSIGNOFF SPSSX-LFor a list of commands to manage subscriptions, send the commandINFO REFCARD

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## Re: interpreting t-test results

 In reply to this post by Talino Bruno Hi Talino, Given that one scale measures only from 1-4, is that a measure of the construct you're interested in, alone ? The other test ranges from 24-120...much bigger...but is it possible to do a similar thing and extract the one question that measures the construct you're interested in, albeit from a different angle ? You might then be able to compare the two tests on that one construct.....although they might still be based on a different metric (the objection raised so far)....isn't this part of what you are after ? But it may be too simple to think that you can extract the question that draws on your construct of interest like this. Just a thought, Martin ----- Original Message ----- From: "Talino Bruno" <[hidden email]> To: <[hidden email]> Sent: Monday, April 06, 2009 12:57 AM Subject: interpreting t-test results >I have set of results for two different tests taken by the same subjects. I > am using the paired sample t-test in SPSS, I assume that is the right one. > I get a significant difference between the two  test, both are > psychological measures, but I would like to know which test gives me the > higher score i.e which psychological construct is most prevalent in my > sample, the test scores are calculated differently one ranges from 1- 4 > and > the other from 24-120. Would I use another analysis to get this answer? > > ===================== > To manage your subscription to SPSSX-L, send a message to > [hidden email] (not to SPSSX-L), with no body text except the > command. To leave the list, send the command > SIGNOFF SPSSX-L > For a list of commands to manage subscriptions, send the command > INFO REFCARD > > ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD
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## Re: interpreting t-test results

In reply to this post by Jims More
is this not what z scores are for?

or am I missing something

M

From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of Jims More
Sent: 06 April 2009 09:56
To: [hidden email]
Subject: Re: interpreting t-test results

 Talino, If you compare ant and elephant, the result is always significant.  Ant is always smaller than elephant.  Your case is analogous to the ant-elephant example.  What do you think?   Jims.  --- On Sun, 5/4/09, Talino Bruno <[hidden email]> wrote: From: Talino Bruno <[hidden email]>Subject: interpreting t-test resultsTo: [hidden email]Received: Sunday, 5 April, 2009, 11:57 PM I have set of results for two different tests taken by the same subjects. Iam using the paired sample t-test in SPSS, I assume that is the right one.I get a significant difference between the two  test, both arepsychological measures, but I would like to know which test gives me thehigher score i.e which psychological construct is most prevalent in mysample, the test scores are calculated differently one ranges from 1- 4 andthe other from 24-120. Would I use another analysis to get this answer?=====================To manage your subscription to SPSSX-L, send a message toLISTSERV@... (not to SPSSX-L), with no body text except thecommand. To leave the list, send the commandSIGNOFF SPSSX-LFor a list of commands to manage subscriptions, send the commandINFO REFCARD

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## Re: interpreting t-test results

 In reply to this post by Talino Bruno After reading some of the other responses, i.e., re-centering the scores so they have a common mean and standard deviation, and picking an item indicative of the "construct of interest", I think finding a third, and maybe a forth, test that you know tests the "constructs of interest" then correlating the scores from the first two test with the new tests.  That should give a more precise indication of which construct in more higher/stronger in the first two. Arthur Kramer "...believe half of what you see and none of what you hear."                   N.Whitfield and B.Strong -----Original Message----- From: SPSSX(r) Discussion [mailto:[hidden email]] On Behalf Of Talino Bruno Sent: Sunday, April 05, 2009 7:58 PM To: [hidden email] Subject: interpreting t-test results I have set of results for two different tests taken by the same subjects. I am using the paired sample t-test in SPSS, I assume that is the right one. I get a significant difference between the two  test, both are psychological measures, but I would like to know which test gives me the higher score i.e which psychological construct is most prevalent in my sample, the test scores are calculated differently one ranges from 1- 4 and the other from 24-120. Would I use another analysis to get this answer? ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD ===================== To manage your subscription to SPSSX-L, send a message to [hidden email] (not to SPSSX-L), with no body text except the command. To leave the list, send the command SIGNOFF SPSSX-L For a list of commands to manage subscriptions, send the command INFO REFCARD
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## Re: interpreting t-test results

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