This worksheet covers merging the data for two surveys which are slightly different. One survey has more questions than the other. It assumes that both surveys contain data to be merged into one survey for analysis.
You may need to merge surveys in these situations:
- Surveys run on an annual basis, to analyse trends through two or more years. (The questionnaire might change slightly from year to year).
- Surveys on one subject but with different focal points (e.g. surveys of users and non-users of a service).
- Surveys conducted for different locations (e.g. a survey of similar tourist attractions which varies between sites).
- Surveys conducted using two different interviewing methods (e.g. kiosk and web).
Summary of steps
- Step 1: Creating a master survey to contain the data for both surveys.
- Step 2: Set up a database link to import the data.
- Step 3: Mapping the variables.
- Step 4: Running the database link.
It is preferable to make a separate master survey to combine your surveys so that both the original surveys remain intact. The master survey will need to contain all the variables and codes in both surveys so that the analysis can be performed correctly.
- Clone the survey with the highest number of variables and name it something that indicates it is the combined survey. Also clone the raw data. This will give you a new copy of your survey including the existing data.
- Open the survey and add in any variables or additional codes that are in the other survey but are not in this survey.
- From the main menu bar click File then Database links. You will see an empty database link window. Click [New…] to create a new database link.
- In the Database Linkage Wizard, select Import From Snap Survey as the Linkage Type.
- Click [Next>]. The list of surveys in the current directory appears.
- Select the survey that you wish to merge. You can browse to a different directory if you need to. Click [Next>] once you have selected a survey.
- You will be asked how you wish to merge the survey. Select Append all cases. This adds all the imported cases as new cases at the end of the survey. Click [Next>].
The next window is where you will match the variables from the survey you are importing the data from to the survey you cloned as the master.
The variables in the survey you are importing from are displayed in the left column and the current survey variables are displayed in the right column.
- Snap will attempt to map any variables from both surveys if the variables are identically named.
- Click each of the variables in the right-hand column. If the variable is a coded question the codes will be displayed in a section below the mapped variables. Check that the codes on the left match the codes on the right.
If there are any blank codes in the right hand column, see the code label where Ice cream should be in the image above, click into the blank area and select the correct code label.
- Click [Next>] to see a summary of the mapped variables. You can also give the Database Linkage an appropriate name in this window.
- Click [Finish] to go back to the Database Links dialog window where you will see the link you have just created.
When a Database link has been set up in the Database Linkage dialog box, it can be run at any time you require.
- If the Database Linkage dialog is not already open, open it by selecting File | Database Links.
- Select your new Survey Import link and click [Run]. A dialog appears showing details of the import.
- You can see the number of cases imported in the Processed Cases section of the Report dialog. Click [OK] to close the Database linkage dialog window.
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