How It Works

WesVar Analysis Steps

Step 1 - Create a WesVar data file.

WesVar reads a variety of file formats. In Figure 1, the user reads the data from an SPSS system file and specifies the full sample weight and case ID variables. The data are a sample of cases from a national health and nutrition survey.

Figure 1: Screen showing importing data files
Figure 1. Indicating the Data File screen for importing files

In Figure 2, the user selects the remaining variables on the input file for later analyses. The file must then be saved as a WesVar data file.

Figure 2: Screen showing moving source variables
Figure 2. Moving source variables into the set of variables for analysis using the mouse or arrow buttons

Step 2 - Create new or import existing replicate weights.

WesVar uses one of five replication methods to calculate variances of survey estimates. To do so, the user first creates replicate weights or imports existing replicate weights.

In Figure 3, the user specifies a variable that defines strata and another that defines the primary sampling units (PSUs). The user also selects a method of variance estimation.

In this example, the sample design had two PSUs in each stratum. Balanced repeated replication (BRR) was specified, and WesVar automatically selected a Hadamard matrix of appropriate size based on the number of strata in the data file.

Figure 3: Screen showing specifying variables to identify stratum
Figure 3. Specifying the variables that identify stratum (VarStrat) and PSU (VarUnit). The BRR method of variance estimation is selected

In Figure 4, replicate weights have been created and are labeled RPL01-RPL24. The user can also type in a different prefix in the Create Weights screen.

Figure 4: Screen showing using the BRR method
Figure 4. Using the BRR method for creating replicate weights. From this screen the user saves the WesVar data file. In this case, the name Demo.var was used

Step 3 - Create a WesVar workbook and specify your analysis.

The user defines analysis requests in workbooks by selecting types of analyses and variables using the mouse. In Figure 5, the user has requested that the means of diastolic and systolic blood pressure be estimated.

Figure 5: Screen showing defining statistics
Figure 5. Defining computed statistics for a table

Step 4 - Run the analysis and view the results.

Next, the user specifies that the means be calculated for each cell of a RACE x SEX table. The table will also contain the estimated total numbers of cases (Sum of Weights/Value) and the row, column, and total percentages for the estimated totals.

Figure 6: Screen showing specifying variables for a table
Figure 6. Specifying the variables that define a table

Figure 7 shows the output screen with mean diastolic and systolic blood pressures for three RACE categories (White & other, Black, and Mexican American) crossed with SEX. Row and column marginals are shown as well as the overall means.

Figure 7: Screen showing an output table
Figure 7. Showing an output table with mean diastolic and systolic blood pressures by race and sex

Table Viewer Utility

Table Viewer is an easy-to-use tool for viewing, printing, and copying the output from one-way, two-way, and three-way tables that have previously been created using WesVar 5. Table Viewer presents the WesVar output in a grid that is easier to work with than the normal WesVar output, which produces one row for each cell of the user’s table request.

To view a table in Table Viewer, the only files necessary are name.wvb (the workbook file from WesVar) and name.001, name.002, etc. (the output files from tables run in WesVar). WesVar data files and the WesVar software itself are not required to view the tables. Note that the table requests in WesVar must be run to create the output files. Workbooks must be saved before the output can be viewed in Table Viewer.

When installing WesVar, the Table Viewer program and some example files are placed in the directory C:\Program Files\WesVar\tabview. To run Table Viewer, double-click on the executable in this directory or go to Start - Programs - WesVar - Launch Table Viewer.exe.

Relabel Utility

The Relabel utility consists of a SAS program and a standalone executable program. Taken together, these let one use information from a SAS format library to relabel the values of a WesVar data set that the user has previously imported from SAS, since WesVar does not keep labels when importing data.

When installing WesVar, the Relabel SAS program, standalone executable and Relabel instructions are placed in the directory C:\Program Files\WesVar\relabel. To view the instructions, double-click on ReadMe.html in this directory, or go to Start - Programs - WesVar - Relabel Instructions.