Chi square or U Test
Locked
 
|
|
|
|
Anthony,
I don't have much time to dive into your problem at the moment, but to start, I don't follow the sentence, "I read 20 words for 30 cases and asked them to tell me the first word that hit them."
Please elaborate.
Ryan
On Wed, Jan 19, 2011 at 4:39 AM, Anthony James <[hidden email]> wrote:
|
Administrator
|
In reply to this post by Anthony James
You say you asked the cases to tell you the first word that hit them. I take it, then, that cases are subjects (or participants) in your study, right? Re the means you computed, I think they are the mean number of subjects (or cases) who selected each category, is that right? Does Phase 2 use the same subjects (cases) in Phase 1? The Mann-Whitney U test is a rank-based alternative to the unpaired (or independent groups) t-test. I.e., it can be used when you have two independent groups of observations. If you have the same subjects in both phases, then a chi-square test of association is out--it requires independence of observations. I'll have a guess at what your data look like. Subject Phase Word Category 1 1 1 2 1 1 2 3 1 1 3 1 1 1 4 2 etc 1 1 20 3 2 1 1 1 2 1 2 3 etc 2 1 20 1 etc, including same type of thing with Phase = 2 This can be reduced to one row per Subject as follows: Subject P1C1 P1C2 P1C3 P2C1 P2C2 P2C3 1 8 7 5 2 10 8 2 4 12 4 4 9 7 3 11 3 6 5 6 9 etc Where P1C1 = Phase 1, Category 1; P1C2 = Phase 1, Category 2, etc; and the data points are counts of how often that category was chosen for each subject. Thus, within a phase, C1, C2, and C3 must sum to 20. Is this what your data look like?
--
Bruce Weaver bweaver@lakeheadu.ca http://sites.google.com/a/lakeheadu.ca/bweaver/ "When all else fails, RTFM." PLEASE NOTE THE FOLLOWING: 1. My Hotmail account is not monitored regularly. To send me an e-mail, please use the address shown above. 2. The SPSSX Discussion forum on Nabble is no longer linked to the SPSSX-L listserv administered by UGA (https://listserv.uga.edu/). |
|
Administrator
|
Anthony, I see you're posting the same question under a new subject. I made a guess as to the structure of your data below, but did not see a response. Note that if you responded to my hotmail address, it is used only for posting to this list via Nabble, and I don't check it regularly--see the note in my signature file. So please respond to the mailing list.
Bruce
--
Bruce Weaver bweaver@lakeheadu.ca http://sites.google.com/a/lakeheadu.ca/bweaver/ "When all else fails, RTFM." PLEASE NOTE THE FOLLOWING: 1. My Hotmail account is not monitored regularly. To send me an e-mail, please use the address shown above. 2. The SPSSX Discussion forum on Nabble is no longer linked to the SPSSX-L listserv administered by UGA (https://listserv.uga.edu/). |
|
|
Anthony,
If Bruce's description of your data is correct, then you should consider fitting a generalized logit model. Why? Because your response consists of unordered categories. But we're not done! Not only are you dealing with a multinomial distribution, but there is likely covariation due to repeated measures. That is, you have (1) collected multiple responses from the same person within Phase I, and if I understand correctly, (2) these same individuals were measured again during Phase II. A generalized logit MIXED model with appropriately specified fixed and random effects can be fit employing the GENLINMIXED procedure in SPSS 19. Ryan On Sun, Jan 23, 2011 at 9:01 AM, Bruce Weaver <[hidden email]> wrote: > Anthony, I see you're posting the same question under a new subject. I made > a guess as to the structure of your data below, but did not see a response. > Note that if you responded to my hotmail address, it is used only for > posting to this list via Nabble, and I don't check it regularly--see the > note in my signature file. So please respond to the mailing list. > > Bruce > > > Bruce Weaver wrote: >> >> >> Anthony James wrote: >>> >>> Dear Colleagues, >>> I have a research design problem. I'd be thankful if you helped. >>> I read 20 words for 30 cases and asked them to tell me the first word >>> that hits them. I categorized the words generated by the participants >>> under 3 categories of 'related words', 'irrelevant words' and >>> 'synonyms/antonyms'. Then I computed the mean of each category over the >>> 30 cases. >>> >> >> You say you asked the cases to tell you the first word that hit them. I >> take it, then, that cases are subjects (or participants) in your study, >> right? >> >> Re the means you computed, I think they are the mean number of subjects >> (or cases) who selected each category, is that right? >> >> >> Anthony James wrote: >>> >>> In Phase 2, I give pictures as prompts to participants instead of words >>> and asked them to tell me the first word that hits them. I categorized >>> the words in the same way and computed the means of the three categories. >>> >> >> Does Phase 2 use the same subjects (cases) in Phase 1? >> >> >> >> Anthony James wrote: >>> >>> Results show that the mean of 'synonyms/antonyms' when words are used as >>> prompts is 19 and its mean is 13 when pictures are used as prompts. This >>> suggests that words generate more synonyms/antonyms than pictures. How >>> can I test the statistical significance of this difference? Is >>> Mann-Whitney U Test the right test? >>> >> >> The Mann-Whitney U test is a rank-based alternative to the unpaired (or >> independent groups) t-test. I.e., it can be used when you have two >> independent groups of observations. >> >> >> Anthony James wrote: >>> >>> I can consider all the 3 categories of words and the two categories of >>> picture and run a 2*3 chi square. However chi square doesn’t give the >>> significance of the difference for each category separately. >>> Â >>> Cheers >>> Anthony >>> Â >>> >> >> If you have the same subjects in both phases, then a chi-square test of >> association is out--it requires independence of observations. >> >> I'll have a guess at what your data look like. >> >> Subject Phase Word Category >> 1 1 1 2 >> 1 1 2 3 >> 1 1 3 1 >> 1 1 4 2 >> etc >> 1 1 20 3 >> 2 1 1 1 >> 2 1 2 3 >> etc >> 2 1 20 1 >> etc, including same type of thing with Phase = 2 >> >> This can be reduced to one row per Subject as follows: >> >> Subject P1C1 P1C2 P1C3 P2C1 P2C2 P2C3 >> 1 8 7 5 2 10 8 >> 2 4 12 4 4 9 7 >> 3 11 3 6 5 6 9 >> etc >> >> Where P1C1 = Phase 1, Category 1; P1C2 = Phase 1, Category 2, etc; and the >> data points are counts of how often that category was chosen for each >> subject. Thus, within a phase, C1, C2, and C3 must sum to 20. >> >> Is this what your data look like? >> >> >> > > > ----- > -- > Bruce Weaver > [hidden email] > http://sites.google.com/a/lakeheadu.ca/bweaver/ > > "When all else fails, RTFM." > > NOTE: My Hotmail account is not monitored regularly. > To send me an e-mail, please use the address shown above. > > -- > View this message in context: http://spssx-discussion.1045642.n5.nabble.com/Chi-square-or-U-Test-tp3347510p3353647.html > Sent from the SPSSX Discussion mailing list archive at Nabble.com. > > ===================== > 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 |
|
|
In reply to this post by Bruce Weaver
Dear Bruce,
I replied to that mail of you and sent it both to your hotmail and lakeheadu mail. Please consider my new posting. It's the same problem but I have worded it differently which I think is clearer. I'd be grateful. I badly need this. Cheers Anthony --- On Sun, 1/23/11, Bruce Weaver <[hidden email]> wrote: > From: Bruce Weaver <[hidden email]> > Subject: Re: Chi square or U Test > To: [hidden email] > Date: Sunday, January 23, 2011, 8:01 AM > Anthony, I see you're posting the > same question under a new subject.� I made > a guess as to the structure of your data below, but did not > see a response. > Note that if you responded to my hotmail address, it is > used only for > posting to this list via Nabble, and I don't check it > regularly--see the > note in my signature file.� So please respond to the > mailing list. > > Bruce > > > Bruce Weaver wrote: > > > > > > Anthony James wrote: > >> > >> Dear Colleagues, > >> I have a research design problem. I'd be thankful > if you helped. > >> I read 20 words for 30 cases and asked them to > tell me the first word > >> that hits them. I categorized the words generated > by the participants > >> under 3 categories of 'related words', 'irrelevant > words' and > >> 'synonyms/antonyms'. Then I computed the mean of > each category over the > >> 30 cases. > >> > > > > You say you asked the cases to tell you the first word > that hit them.� I > > take it, then, that cases are subjects (or > participants) in your study, > > right? > > > > Re the means you computed, I think they are the mean > number of subjects > > (or cases) who selected each category, is that right? > > > > > > Anthony James wrote: > >> > >> In Phase 2, I give pictures as prompts to > participants instead of words > >> and asked them to tell me the first word that hits > them. I categorized > >> the words in the same way and computed the means > of the three categories. > >> > > > > Does Phase 2 use the same subjects (cases) in Phase > 1? > > > > > > > > Anthony James wrote: > >> > >> Results show that the mean of 'synonyms/antonyms' > when words are used as > >> prompts is 19 and its mean is 13 when pictures are > used as prompts. This > >> suggests that words generate more > synonyms/antonyms than pictures. How > >> can I test the statistical significance of this > difference? Is > >> Mann-Whitney U Test the right test? > >> > > > > The Mann-Whitney U test is a rank-based alternative to > the unpaired (or > > independent groups) t-test.� I.e., it can be used > when you have two > > independent groups of observations. > > > > > > Anthony James wrote: > >> > >> I can consider all the 3 categories of words and > the two categories of > >> picture and run a 2*3 chi square. However chi > square doesn’t give the > >> significance of the difference for each category > separately. > >>  > >> Cheers > >> Anthony > >>  > >> > > > > If you have the same subjects in both phases, then a > chi-square test of > > association is out--it requires independence of > observations. > > > > I'll have a guess at what your data look like. > > > > Subject� Phase Word� Category > > 1� � � � � � 1� > � � � 1� � � � � 2 > > 1� � � � � � 1� > � � � 2� � � � � 3 > > 1� � � � � � 1� > � � � 3� � � � � 1 > > 1� � � � � � 1� > � � � 4� � � � � 2 > > etc > > 1� � � � � � 1� > � � � 20� � � � � 3 > > 2� � � � � � 1� > � � � � � 1� � � � > � � � 1 > > 2� � � � � � 1� > � � � � � 2� � � � > � � � 3 > > etc > > 2� � � � � � 1� > � � � 20� � � � � 1 > > etc, including same type of thing with Phase = 2 > > > > This can be reduced to one row per Subject as > follows: > > > > Subject P1C1� P1C2� P1C3� P2C1 P2C2 > P2C3 > > 1� � � � � 8� � > � � 7� � � 5� � � > � 2� � � � 10� � � 8 > > 2� � � � � 4� � > � 12� � � 4� � � � > 4� � � � � 9� � � 7 > > 3� � � � � � 11� > � � � � 3� � � 6� > � � � 5� � > � � � 6� � � 9 > > etc > > > > Where P1C1 = Phase 1, Category 1; P1C2 = Phase 1, > Category 2, etc; and the > > data points are counts of how often that category was > chosen for each > > subject.� Thus, within a phase, C1, C2, and C3 > must sum to 20. > > > > Is this what your data look like? > > > > > > > > > ----- > -- > Bruce Weaver > [hidden email] > http://sites.google.com/a/lakeheadu.ca/bweaver/ > > "When all else fails, RTFM." > > NOTE: My Hotmail account is not monitored regularly. > To send me an e-mail, please use the address shown above. > > -- > View this message in context: http://spssx-discussion.1045642.n5.nabble.com/Chi-square-or-U-Test-tp3347510p3353647.html > Sent from the SPSSX Discussion mailing list archive at > Nabble.com. > > ===================== > 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 |
|
Administrator
|
In reply to this post by Ryan
Hi Ryan. If my description is correct, a two-factor (Phase x Category) repeated measures ANOVA would probably yield a reasonably good model too, I think. Ray Koopman, whom you know from his postings on other lists, once pointed to a paper by Shaffer (1981, "The analysis of variance mixed model with allocated observations") for situations like this, where the k-th score within a subject is perfectly predicted given the first k-1 scores. (I.e., here, the 3 scores within a phase must sum to 20.) I see there is a more recent simulation paper that also concludes ANOVA works well for this situation.
http://psycnet.apa.org/?fa=main.doiLanding&doi=10.1037/1082-989X.2.2.200 HTH.
--
Bruce Weaver bweaver@lakeheadu.ca http://sites.google.com/a/lakeheadu.ca/bweaver/ "When all else fails, RTFM." PLEASE NOTE THE FOLLOWING: 1. My Hotmail account is not monitored regularly. To send me an e-mail, please use the address shown above. 2. The SPSSX Discussion forum on Nabble is no longer linked to the SPSSX-L listserv administered by UGA (https://listserv.uga.edu/). |
|
|
Hi, Bruce:
In general, I think the approach you've suggested should work. I don't have time right now to read the simulation study to which you linked in the previous post. I will concur, however, that the abstract seems to support use of a GLM. I guess my primary concern would be the extent to which statistical power is compromised by how well the assumptions of the specificifed GLM-ANOVA are met. Ryan On Mon, Jan 24, 2011 at 9:28 AM, Bruce Weaver <[hidden email]> wrote: > Hi Ryan. If my description is correct, a two-factor (Phase x Category) > repeated measures ANOVA would probably yield a reasonably good model too, I > think. Ray Koopman, whom you know from his postings on other lists, once > pointed to a paper by Shaffer (1981, "The analysis of variance mixed model > with allocated observations") for situations like this, where the k-th score > within a subject is perfectly predicted given the first k-1 scores. (I.e., > here, the 3 scores within a phase must sum to 20.) I see there is a more > recent simulation paper that also concludes ANOVA works well for this > situation. > > http://psycnet.apa.org/?fa=main.doiLanding&doi=10.1037/1082-989X.2.2.200 > > HTH. > > > > R B wrote: >> >> Anthony, >> >> If Bruce's description of your data is correct, then you should >> consider fitting a generalized logit model. Why? Because your response >> consists of unordered categories. But we're not done! Not only are you >> dealing with a multinomial distribution, but there is likely >> covariation due to repeated measures. That is, you have (1) collected >> multiple responses from the same person within Phase I, and if I >> understand correctly, (2) these same individuals were measured again >> during Phase II. >> >> A generalized logit MIXED model with appropriately specified fixed and >> random effects can be fit employing the GENLINMIXED procedure in SPSS >> 19. >> >> Ryan >> >> On Sun, Jan 23, 2011 at 9:01 AM, Bruce Weaver <[hidden email]> >> wrote: >>> Anthony, I see you're posting the same question under a new subject. I >>> made >>> a guess as to the structure of your data below, but did not see a >>> response. >>> Note that if you responded to my hotmail address, it is used only for >>> posting to this list via Nabble, and I don't check it regularly--see the >>> note in my signature file. So please respond to the mailing list. >>> >>> Bruce >>> >>> >>> Bruce Weaver wrote: >>>> >>>> >>>> Anthony James wrote: >>>>> >>>>> Dear Colleagues, >>>>> I have a research design problem. I'd be thankful if you helped. >>>>> I read 20 words for 30 cases and asked them to tell me the first word >>>>> that hits them. I categorized the words generated by the participants >>>>> under 3 categories of 'related words', 'irrelevant words' and >>>>> 'synonyms/antonyms'. Then I computed the mean of each category over the >>>>> 30 cases. >>>>> >>>> >>>> You say you asked the cases to tell you the first word that hit them. I >>>> take it, then, that cases are subjects (or participants) in your study, >>>> right? >>>> >>>> Re the means you computed, I think they are the mean number of subjects >>>> (or cases) who selected each category, is that right? >>>> >>>> >>>> Anthony James wrote: >>>>> >>>>> In Phase 2, I give pictures as prompts to participants instead of words >>>>> and asked them to tell me the first word that hits them. I categorized >>>>> the words in the same way and computed the means of the three >>>>> categories. >>>>> >>>> >>>> Does Phase 2 use the same subjects (cases) in Phase 1? >>>> >>>> >>>> >>>> Anthony James wrote: >>>>> >>>>> Results show that the mean of 'synonyms/antonyms' when words are used >>>>> as >>>>> prompts is 19 and its mean is 13 when pictures are used as prompts. >>>>> This >>>>> suggests that words generate more synonyms/antonyms than pictures. How >>>>> can I test the statistical significance of this difference? Is >>>>> Mann-Whitney U Test the right test? >>>>> >>>> >>>> The Mann-Whitney U test is a rank-based alternative to the unpaired (or >>>> independent groups) t-test. I.e., it can be used when you have two >>>> independent groups of observations. >>>> >>>> >>>> Anthony James wrote: >>>>> >>>>> I can consider all the 3 categories of words and the two categories of >>>>> picture and run a 2*3 chi square. However chi square doesn’t give the >>>>> significance of the difference for each category separately. >>>>> Â >>>>> Cheers >>>>> Anthony >>>>> Â >>>>> >>>> >>>> If you have the same subjects in both phases, then a chi-square test of >>>> association is out--it requires independence of observations. >>>> >>>> I'll have a guess at what your data look like. >>>> >>>> Subject Phase Word Category >>>> 1 1 1 2 >>>> 1 1 2 3 >>>> 1 1 3 1 >>>> 1 1 4 2 >>>> etc >>>> 1 1 20 3 >>>> 2 1 1 1 >>>> 2 1 2 3 >>>> etc >>>> 2 1 20 1 >>>> etc, including same type of thing with Phase = 2 >>>> >>>> This can be reduced to one row per Subject as follows: >>>> >>>> Subject P1C1 P1C2 P1C3 P2C1 P2C2 P2C3 >>>> 1 8 7 5 2 10 8 >>>> 2 4 12 4 4 9 7 >>>> 3 11 3 6 5 6 9 >>>> etc >>>> >>>> Where P1C1 = Phase 1, Category 1; P1C2 = Phase 1, Category 2, etc; and >>>> the >>>> data points are counts of how often that category was chosen for each >>>> subject. Thus, within a phase, C1, C2, and C3 must sum to 20. >>>> >>>> Is this what your data look like? >>>> >>>> >>>> >>> >>> >>> ----- >>> -- >>> Bruce Weaver >>> [hidden email] >>> http://sites.google.com/a/lakeheadu.ca/bweaver/ >>> >>> "When all else fails, RTFM." >>> >>> NOTE: My Hotmail account is not monitored regularly. >>> To send me an e-mail, please use the address shown above. >>> >>> -- >>> View this message in context: >>> http://spssx-discussion.1045642.n5.nabble.com/Chi-square-or-U-Test-tp3347510p3353647.html >>> Sent from the SPSSX Discussion mailing list archive at Nabble.com. >>> >>> ===================== >>> 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 >> >> > > > ----- > -- > Bruce Weaver > [hidden email] > http://sites.google.com/a/lakeheadu.ca/bweaver/ > > "When all else fails, RTFM." > > NOTE: My Hotmail account is not monitored regularly. > To send me an e-mail, please use the address shown above. > > -- > View this message in context: http://spssx-discussion.1045642.n5.nabble.com/Chi-square-or-U-Test-tp3347510p3354708.html > Sent from the SPSSX Discussion mailing list archive at Nabble.com. > > ===================== > 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 |
«
Return to SPSSX Discussion
|
1 view|%1 views
| Free forum by Nabble | Edit this page |