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  • MSP output does not show scalability coefficient

    Dear colleagues,

    I have tried to do a Mokken Scale Analysis with MSP in stata. All seems to work ok, except I don't get scalability coefficients for each generated scale (i.e. the Loevinger's H at the bottom of each scale). See attachment for output. I can't find anything on why this may occur, so I was hoping someone here might be able to help.

    Many thanks,
    Joost
    Attached Files

  • #2
    Joost,

    The FAQ asks us not to post attachments like screenshots. You can report your output in the code delimiters (see my signature for details).

    The MSP package, by Jean-Benoit Hardouin and available on Statistical Software Components, does Mokken scale analysis, a type of non-parametric item response theory.* You use the -msp- command in the package, which is an automated scaling procedure that selects items stepwise and proposes one or more scales. While the H-coefficient (this indicates how strongly the items in each scale scale together in a Guttman-like sense (this is a simplification)) isn't printed in your screen, if you type

    Code:
    return list
    , you should see some scalars (like 1x1 vectors) called r(H1), r(H2), etc. You can ask Stata to print a scalar by typing

    Code:
    di r(H1)
    in the command line. -di- is shorthand for display, although you can obviously type -display- if you prefer.

    * Not trying to be tendentious, but this is to make things easier for other readers who have no idea what MSP is.
    Please use the code delimiters to show code and results - use the # button on the formatting toolbar, between the " (double quote) and <> buttons.

    Please use the command -dataex- to show a representative sample of data; it is installed already if you have Stata 14.2 or 15.1, else you can install it by typing

    Code:
    ssc install dataex

    Comment


    • #3
      Many thanks Weiwen for your answer and apologies for not posting my output in the correct manner.

      I have used the method you suggest, but exactly the same comes out after "return list" - ie output with the H coefficients left blank. Any other suggestions?

      Comment


      • #4
        And here is the output (hopefully) in the correct fashion:

        Code:
        . msp qid12_1 - qid12_20 lifestyle_other polpart_other, c(.4)
        
        Scale: 1
        ----------
        Significance level: 0.000216
        The two first items selected in the scale 1 are qid12_1 and qid12_3 (Hjk=0.7920)
        The following items are excluded at this step: qid12_6 qid12_8 qid12_10 qid12_11 qid12_12 qid12_13 qid12_1
        > 4 qid12_15 qid12_16 lifestyle_other
        Significance level: 0.000207
        The item qid12_2 is selected in the scale 1      Hj=0.4285      H=     .
        Significance level: 0.000200
        None new item can be selected in the scale 1 because all the Hj are lesser than .4 or none new item has
        all the related Hjk coefficients significantly greater than 0
        .
        
                                          Observed    Expected                                      Number
                              Easyness     Guttman     Guttman    Loevinger               H0: Hj<=0  of NS
        Item          Obs      P(Xj=1)      errors      errors      H coeff     z-stat.     p-value    Hjk
        ---------------------------------------------------------------------------------------------------
        qid12_2       2113      0.3365         281      491.66      0.42847     18.2554     0.00000      0
        qid12_1       2113      0.1159         130      350.05      0.62862     23.5504     0.00000      0
        qid12_3       2113      0.2347         229      516.59      0.55671     25.8566     0.00000      0
        ---------------------------------------------------------------------------------------------------
        Scale         2113                     320      679.15                  27.3778     0.00000
        
        
        Scale: 2
        ----------
        Significance level: 0.000292
        The two first items selected in the scale 2 are qid12_6 and qid12_7 (Hjk=0.6998)
        The following items are excluded at this step: lifestyle_other
        Significance level: 0.000267
        The item qid12_5 is selected in the scale 2      Hj=0.4865      H=     .
        Significance level: 0.000248
        None new item can be selected in the scale 2 because all the Hj are lesser than .4 or none new item has
        all the related Hjk coefficients significantly greater than 0
        .
        
                                          Observed    Expected                                      Number
                              Easyness     Guttman     Guttman    Loevinger               H0: Hj<=0  of NS
        Item          Obs      P(Xj=1)      errors      errors      H coeff     z-stat.     p-value    Hjk
        ---------------------------------------------------------------------------------------------------
        qid12_5       2113      0.2120         228      443.99      0.48647     18.8475     0.00000      0
        qid12_6       2113      0.6351          93      293.37      0.68299     16.3337     0.00000      0
        qid12_7       2113      0.1685         213      410.42      0.48102     18.1653     0.00000      0
        ---------------------------------------------------------------------------------------------------
        Scale         2113                     267      573.89                  21.7024     0.00000
        
        
        Scale: 3
        ----------
        Significance level: 0.000417
        The two first items selected in the scale 3 are qid12_11 and qid12_12 (Hjk=0.6947)
        Significance level: 0.000373
        The item qid12_10 is selected in the scale 3     Hj=0.5197      H=     .
        Significance level: 0.000340
        The item qid12_13 is selected in the scale 3     Hj=0.4677      H=     .
        The following items are excluded at this step: qid12_4
        Significance level: 0.000316
        The item qid12_14 is selected in the scale 3     Hj=0.4793      H=     .
        The following items are excluded at this step: qid12_19
        Significance level: 0.000299
        The item qid12_15 is selected in the scale 3     Hj=0.4292      H=     .
        Significance level: 0.000286
        The item qid12_16 is selected in the scale 3     Hj=0.4148      H=     .
        The following items are excluded at this step: qid12_18
        Significance level: 0.000276
        The item polpart_other is selected in the scale 3Hj=0.4044      H=     .
        Significance level: 0.000269
        None new item can be selected in the scale 3 because all the Hj are lesser than .4 or none new item has
        all the related Hjk coefficients significantly greater than 0
        .
        
                                          Observed    Expected                                      Number
                              Easyness     Guttman     Guttman    Loevinger               H0: Hj<=0  of NS
        Item          Obs      P(Xj=1)      errors      errors      H coeff     z-stat.     p-value    Hjk
        ---------------------------------------------------------------------------------------------------
        polpart_other 2113      0.1368         610     1024.15      0.40438     20.3808     0.00000      0
        qid12_16      2113      0.2504        1038     1694.74      0.38752     26.1908     0.00000      0
        qid12_15      2113      0.5712        1464     2603.72      0.43773     40.5256     0.00000      0
        qid12_14      2113      0.6001        1239     2517.00      0.50775     45.8341     0.00000      0
        qid12_13      2113      0.5329        1317     2643.32      0.50176     46.8422     0.00000      0
        qid12_10      2113      0.4633        1627     2584.05      0.37037     33.8154     0.00000      0
        qid12_11      2113      0.6058        1300     2488.36      0.47757     42.7070     0.00000      0
        qid12_12      2113      0.4326        1181     2499.36      0.52748     46.8354     0.00000      0
        ---------------------------------------------------------------------------------------------------
        Scale         2113                    4888     9027.35                  77.0023     0.00000
        
        
        Scale: 4
        ----------
        Significance level: 0.001786
        The two first items selected in the scale 4 are qid12_18 and qid12_20 (Hjk=0.6943)
        The following items are excluded at this step: qid12_8 lifestyle_other
        Significance level: 0.001563
        The item qid12_19 is selected in the scale 4     Hj=0.6568      H=     .
        Significance level: 0.001429
        None new item can be selected in the scale 4 because all the Hj are lesser than .4 or none new item has
        all the related Hjk coefficients significantly greater than 0
        .
        
                                          Observed    Expected                                      Number
                              Easyness     Guttman     Guttman    Loevinger               H0: Hj<=0  of NS
        Item          Obs      P(Xj=1)      errors      errors      H coeff     z-stat.     p-value    Hjk
        ---------------------------------------------------------------------------------------------------
        qid12_19      2113      0.3961         273      795.40      0.65678     35.2912     0.00000      0
        qid12_18      2113      0.4321         252      776.34      0.67540     35.2254     0.00000      0
        qid12_20      2113      0.2508         205      621.05      0.66991     29.9864     0.00000      0
        ---------------------------------------------------------------------------------------------------
        Scale         2113                     365     1096.39                  41.1054     0.00000
        
        
        Scale: 5
        ----------
        Significance level: 0.005000
        The two first items selected in the scale 5 are qid12_9 and qid12_17 (Hjk=0.6270)
        Significance level: 0.003846
        None new item can be selected in the scale 5 because all the Hj are lesser than .4 or none new item has
        all the related Hjk coefficients significantly greater than 0
        .
        
                                          Observed    Expected                                      Number
                              Easyness     Guttman     Guttman    Loevinger               H0: Hj<=0  of NS
        Item          Obs      P(Xj=1)      errors      errors      H coeff     z-stat.     p-value    Hjk
        ---------------------------------------------------------------------------------------------------
        qid12_9       2113      0.4468         162      434.29      0.62698     24.6524     0.00000      0
        qid12_17      2113      0.3715         162      434.29      0.62698     24.6524     0.00000      0
        ---------------------------------------------------------------------------------------------------
        Scale         2113                     162      434.29                  24.6524     0.00000
        
        
        Scale: 6
        ----------
        Significance level: 0.016667
        None pair of items has a significantly positive Hjk coefficient.
        
        . 
        end of do-file
        
        . return list
        
        scalars:
                        r(dim) =  6
                         r(H5) =  .
                   r(nbitems5) =  2
                         r(H4) =  .
                   r(nbitems4) =  3
                         r(H3) =  .
                   r(nbitems3) =  8
                         r(H2) =  .
                   r(nbitems2) =  3
                         r(H1) =  .
                   r(nbitems1) =  3
        
        macros:
                  r(scalenum5) : "9 17"
                     r(scale5) : "qid12_9 qid12_17"
                  r(scalenum4) : "19 18 20"
                     r(scale4) : "qid12_19 qid12_18 qid12_20"
                  r(scalenum3) : "22 16 15 14 13 10 11 12"
                     r(scale3) : "polpart_other qid12_16 qid12_15 qid12_14 qid12_13 qid12_10 qid12_11 qid12_12"
                  r(scalenum2) : "5 6 7"
                     r(scale2) : "qid12_5 qid12_6 qid12_7"
                  r(scalenum1) : "2 1 3"
                     r(scale1) : "qid12_2 qid12_1 qid12_3"
        
        matrices:
                  r(selection) :  1 x 22
        
        . di r(H1)
        .

        Comment


        • #5
          Huh, I didn't see that coming! I would take this up with the author of the command. I don't dispute that the scale H coefficients are missing, but the manual seems to be pretty clear that they should be returned in those scalars. I wonder if you have any observations that are missing some of the questions, which could cause the command to behave strangely. However, if I recall correctly, the command's default should be listwise deletion (I don't use the automated selection procedure, so I don't know for sure).
          Please use the code delimiters to show code and results - use the # button on the formatting toolbar, between the " (double quote) and <> buttons.

          Please use the command -dataex- to show a representative sample of data; it is installed already if you have Stata 14.2 or 15.1, else you can install it by typing

          Code:
          ssc install dataex

          Comment

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