Examples


Example 68.1. Two-Way Tables

This example uses the SIS_Survey data set from the section 'Getting Started' on page 4185. The data set contains results from a customer satisfaction survey for a student information system (SIS).

The following PROC SURVEYFREQ statements request a two-way table for the variables Department by Response and customize the crosstabulation table display.

  proc surveyfreq data=SIS_Survey;   tables  Department * Response /   cv deff nowt nostd nototal;   strata  State NewUser / list;   cluster School;   weight  SamplingWeight;   run;  

The TABLES statement requests a two-way table of Department by Response . The CV option requests coefficients of variation for the percentage estimates. The DEFF option requests design effects for the percentage estimates. The NOWT option suppresses display of the weighted frequencies, and the NOSTD option suppresses display of standard errors for the estimates. The NOTOTAL option suppresses the row totals, column totals, and overall totals.

The WCHISQ option requests a Wald chi-square test of association between the variables Department and Response .

The STRATA, CLUSTER, and WEIGHT statements provide sample design information to the procedure, so that the analysis will be done according to the sample design used for the survey. The STRATA statement names the variables State and NewUser , which identify the first-stage strata. The LIST option in the STRATA statement requests a Stratum Information table. The CLUSTER statement identifies School as the cluster or first-stage sampling unit. The WEIGHT statement names the sampling weight variable.

Output 68.1.1 displays the Data Summary and Stratum Information tables produced by PROC SURVEYFREQ. The Stratum Information table lists the six strata in the survey and shows the number of clusters, or schools , and the number of observations in each stratum.

Output 68.1.1: Data Summary and Stratum Information
start example
  School Information System Survey   The SURVEYFREQ Procedure   Data Summary   Number of Strata                   6   Number of Clusters               370   Number of Observations          1850   Sum of Weights            38899.6482   Stratum Information   Stratum                                 Number of    Number of   Index     State    NewUser                   Obs     Clusters   --------------------------------------------------------------   1       GA       Renewal Customer          315           63   2       GA       New Customer              355           71   3       NC       Renewal Customer          280           56   4       NC       New Customer              420           84   5       SC       Renewal Customer          210           42   6       SC       New Customer              270           54   --------------------------------------------------------------  
end example
 

Output 68.1.2 displays the two-way table of Department by Response . According to the TABLES statement options specified, this two-way table includes coefficients of variation and design effects for the percentage estimates, and it does not show the weighted frequencies or the standard errors of the estimates.

Output 68.1.2: Two-Way Table of Department by Response
start example
  School Information System Survey   The SURVEYFREQ Procedure   Table of Department by Response   CV for     Design   Department           Response    Frequency   Percent     Percent     Effect   -------------------------------------------------------------------------------   Faculty   Very Unsatisfied          209   13.4987      0.0865     2.1586   Unsatisfied          203   13.0710      0.0868     2.0962   Neutral          346   22.4127      0.0629     2.1157   Satisfied          254   16.2006      0.0806     2.3232   Very Satisfied           98    6.2467      0.1362     2.2842   -------------------------------------------------------------------------------   Admin/Guidance   Very Unsatisfied           95    3.6690      0.1277     1.1477   Unsatisfied          123    4.6854      0.1060     1.0211   Neutral          235    9.1838      0.0700     0.9166   Satisfied          201    7.7305      0.0756     0.8848   Very Satisfied           86    3.3016      0.1252     0.9892   -------------------------------------------------------------------------------  
end example
 

The following PROC SURVEYFREQ statements request a two-way table of Department by Response that includes row percentages, and also a Wald chi-square test of association between the two table variables.

  proc surveyfreq data=SIS_Survey nosummary;   tables Department * Response /   row nowt wchisq;   strata State NewUser;   cluster School;   weight SamplingWeight;   run;  

Output 68.1.3 displays the two-way table. The row percentages show the distribution of Response for Department = 'Faculty' and for Department = 'Admin/Guidance'.

Output 68.1.3: Table of Department by Response with Row Percentages
start example
  School Information System Survey   The SURVEYFREQ Procedure   Table of Department by Response   Std Err of        Row     Std Err of   Department            Response     Frequency    Percent       Percent    Percent    Row Percent   ---------------------------------------------------------------------------------------------------   Faculty    Very Unsatisfied           209    13.4987        1.1675    18.8979         1.6326   Unsatisfied           203    13.0710        1.1350    18.2992         1.5897   Neutral           346    22.4127        1.4106    31.3773         1.9705   Satisfied           254    16.2006        1.3061    22.6805         1.8287   Very Satisfied            98     6.2467        0.8506     8.7452         1.1918   Total          1110    71.4297        0.1468    100.000   ---------------------------------------------------------------------------------------------------   Admin/Guidance    Very Unsatisfied            95     3.6690        0.4684    12.8419         1.6374   Unsatisfied           123     4.6854        0.4966    16.3995         1.7446   Neutral           235     9.1838        0.6430    32.1447         2.2300   Satisfied           201     7.7305        0.5842    27.0579         2.0406   Very Satisfied            86     3.3016        0.4133    11.5560         1.4466   Total           740    28.5703        0.1468    100.000   ---------------------------------------------------------------------------------------------------   Total    Very Unsatisfied           304    17.1676        1.2872   Unsatisfied           326    17.7564        1.2712   Neutral           581    31.5965        1.5795   Satisfied           455    23.9311        1.4761   Very Satisfied           184     9.5483        0.9523   Total          1850    100.000   ---------------------------------------------------------------------------------------------------  
end example
 

Output 68.1.4 displays the Wald chi-square test for association between Department and Response . The Wald chi-square is 11.44, and the corresponding adjusted F value is 2.84 with a p -value of .0243. This indicates a significant association between department (faculty or admin/guidance) and satisfaction with the student information system.

Output 68.1.4: Wald Chi-Square Test
start example
  Table of Department by Response   Wald Chi-Square Test   Chi-Square      11.4454   F Value          2.8613   Num DF                4   Den DF              364   Pr > F           0.0234   Adj F Value      2.8378   Num DF                4   Den DF              361   Pr > Adj F       0.0243   Sample Size = 1850  
end example
 

Example 68.2. Multiway Tables

Continuing to use the SIS_Survey data set from the section 'Getting Started' on page 4185, this example shows how to produce multiway tables. The following PROC SURVEYFREQ statements request a table of Department by SchoolType by Response for the student information system survey.

  proc surveyfreq data=SIS_Survey;   tables  Department * SchoolType * Response   SchoolType * Response;   strata  State NewUser;   cluster School;   weight  SamplingWeight;   run;  

The TABLES statement requests a multiway table with SchoolType as the row variable, Response as the column variable, and Department as the layer variable. This request produces a separate two-way table of SchoolType by Response for each level of the variable Department . The TABLES statement also requests a two-way table of SchoolType by Response , which totals the multiway table over both levels of Department . As in the previous examples, the STRATA, CLUSTER, and WEIGHT statements provide sample design information, so that the analysis will be done according to the design used for this survey.

Output 68.2.1 displays the multiway table produced by PROC SURVEYFREQ, which includes a table of SchoolType by Response for Department = 'Faculty' and for Department = 'Admin/Guidance'.

Output 68.2.1: Multiway Table of Department by SchoolType by Response
start example
  School Information System Survey   The SURVEYFREQ Procedure   Table of SchoolType by Response   Controlling for Department=Faculty   Weighted    Std Dev of               Std Err of   SchoolType            Response     Frequency     Frequency      Wgt Freq    Percent       Percent   ----------------------------------------------------------------------------------------------------   Middle School    Very Unsatisfied            74          1846     301.22637     6.6443        1.0838   Unsatisfied            78          1929     283.11476     6.9428        1.0201   Neutral           130          3289     407.80855    11.8369        1.4652   Satisfied           113          2795     368.85087    10.0597        1.3288   Very Satisfied            55          1378     261.63311     4.9578        0.9411   Total           450         11237     714.97120    40.4415        2.5713   ----------------------------------------------------------------------------------------------------   High School    Very Unsatisfied           135          3405     389.42313    12.2536        1.3987   Unsatisfied           125          3155     384.56734    11.3563        1.3809   Neutral           216          5429     489.37826    19.5404        1.7564   Satisfied           141          3507     417.54773    12.6208        1.5040   Very Satisfied            43          1052     221.59367     3.7874        0.7984   Total           660         16549     719.61536    59.5585        2.5713   ----------------------------------------------------------------------------------------------------   Total    Very Unsatisfied           209          5251     454.82598    18.8979        1.6326   Unsatisfied           203          5085     442.39032    18.2992        1.5897   Neutral           346          8718     550.81735    31.3773        1.9705   Satisfied           254          6302     507.01711    22.6805        1.8287   Very Satisfied            98          2430     330.97602     8.7452        1.1918   Total          1110         27786     119.25529    100.000   ----------------------------------------------------------------------------------------------------   Table of SchoolType by Response   Controlling for Department=Admin/Guidance   Weighted    Std Dev of               Std Err of   SchoolType            Response     Frequency     Frequency      Wgt Freq    Percent       Percent   ----------------------------------------------------------------------------------------------------   Middle School    Very Unsatisfied            42     649.43427     133.06194     5.8435        1.1947   Unsatisfied            31     460.35557     100.80158     4.1422        0.9076   Neutral           104          1568     186.99946    14.1042        1.6804   Satisfied            84          1269     165.71127    11.4142        1.4896   Very Satisfied            39     574.93878     110.37243     5.1732        0.9942   Total           300          4521     287.86832    40.6774        2.5801   ----------------------------------------------------------------------------------------------------   High School    Very Unsatisfied            53     777.77725     136.41869     6.9983        1.2285   Unsatisfied            92          1362     175.40862    12.2573        1.5806   Neutral           131          2005     212.34804    18.0404        1.8990   Satisfied           117          1739     190.07798    15.6437        1.7118   Very Satisfied            47     709.37033     126.54394     6.3828        1.1371   Total           440          6593     288.92483    59.3226        2.5801   ----------------------------------------------------------------------------------------------------   Total    Very Unsatisfied            95          1427     182.28132    12.8419        1.6374   Unsatisfied           123          1823     193.43045    16.3995        1.7446   Neutral           235          3572     250.22739    32.1447        2.2300   Satisfied           201          3007     226.82311    27.0579        2.0406   Very Satisfied            86          1284     160.83434    11.5560        1.4466   Total           740         11114      60.78850    100.000   ----------------------------------------------------------------------------------------------------  
end example
 

Example 68.3. Output Data Sets

PROC SURVEYFREQ uses the Output Delivery System (ODS) to create output data sets. This is a departure from older SAS procedures that provide OUTPUT statements for similar functionality. Using ODS, you can create a SAS data set from any piece of PROC SURVEYFREQ output. For more information on ODS, see Chapter 14, 'Using the Output Delivery System.'

When selecting tables for ODS output data set, you reference tables by their ODS table names. Each table created by PROC SURVEYFREQ is assigned a name , and the section 'ODS Table Names' on page 4230 lists the table names.

To save the one-way table of Response from Figure 68.3 in an output data set, use an ODS OUTPUT statement as follows :

  proc surveyfreq data=SIS_Survey;   tables  Response / cl nowt;   ods output OneWay=ResponseTable;   strata  State NewUser;   cluster School;   weight  SamplingWeight;   run;  

Output 68.3.1 displays the output data set ResponseTable , which contains the one-way table of Response . This data set has six observations, and each of these observations corresponds to a row of the one-way table. The first five observations correspond to the five levels of Response , as they are ordered in the display, and the last observation corresponds to the overall total, which is the last row of the table. The data set ResponseTable includes a variable corresponding to each column of the one-way table. For example, the variable Percent contains the percentage estimates, and the variables LowerCL and UpperCL contain the lower and upper confidence limits for the percentage estimates.

Output 68.3.1: ResponseTable Output Data Set
start example
  Obs        Table             Response         Frequency    Percent     StdErr    LowerCL    UpperCL   1     Table Response    Very Unsatisfied           304    17.1676     1.2872    14.6364    19.6989   2     Table Response    Unsatisfied                326    17.7564     1.2712    15.2566    20.2562   3     Table Response    Neutral                    581    31.5965     1.5795    28.4904    34.7026   4     Table Response    Satisfied                  455    23.9311     1.4761    21.0285    26.8338   5     Table Response    Very Satisfied             184     9.5483     0.9523     7.6756    11.4210   6     Table Response                   .          1850    100.000      _          _         _  
end example
 

PROC SURVEYFREQ also creates a table summary that is not displayed. Some of the information in this table is similar to that contained in the 'Data Summary' table, but the table summary describes data used to analyze the specified table, while the data summary describes the entire input data set. Due to missing values, for example, the number of observations (or strata or clusters) used to analyze a particular table may differ from the number of observations (or strata or clusters) reported for the input data set in the 'Data Summary' table. See the section 'Missing Values' on page 4205 for more details. If you request confidence limits, the 'Table Summary' table also contains the degrees of freedom and the t -value used to compute the confidence limits.

The following statements store the nondisplayed 'Table Summary' table in the output data set ResponseSummary .

  proc surveyfreq data=SIS_Survey;   tables  Response / cl nowt;   ods output TableSummary=ResponseSummary;   strata  State NewUser;   cluster School;   weight  SamplingWeight;   run;  

Output 68.3.2 displays the output data set ResponseSummary .

Output 68.3.2: ResponseSummary Output Data Set
start example
  Number     Number      Degrees   Number of            of       of             of        t   Obs        Table         Observations      Strata    Clusters     Freedom    Percentile   1     Table Response          1850             6         370         364     1.966503  
end example
 



SAS.STAT 9.1 Users Guide (Vol. 6)
SAS.STAT 9.1 Users Guide (Vol. 6)
ISBN: N/A
EAN: N/A
Year: 2004
Pages: 127

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