The best way of analysing post codes / zip codes is to create a Derived Single variable.

There are some considerations to take into account when analysing post/zip codes in Snap.

  1. Snap is case sensitive, therefore, if the data has been entered into the post/zip code question in a variety of ways (e.g. BS8, bs8 or even Bs8), you will need to account for every possible variation in order to capture all the data.
  2. If your post/zip codes include letter combinations that could be found in another post/zip code (e.g. B7 and BS7), you should put the more complex codes before the simpler ones (i.e. BS7 should be inserted before B7).
  3. If your post/zip code include number combinations that could be found in another post/zip code (e.g. SW1 and SW11), you should put a space after the shorter code (e.g. “SW1” and “SW11”).
  4. Additionally, It is always best to enter each post/zip code in inverted commas (e.g. “BS8 9QT”).

To create the derived single variable, please follow the steps below; which will categorise the post/zip codes by area.


  1. Open the Variables window variables button and click  plus | add  to add a new variable.
  2. Select Derived from the Type dropdown and Single from the Response dropdown (each respondent will only fall into one of the new codes).
  3. Enter some text in the Label box that describes what this derived variable is for.
    Variable details window
    (Please note that Derived variables are automatically named starting from V1.)
  4. Click into the label column next to code 1 and type in the first post/zip code area you want to categorise.
  5. Tab across to the Values column and type in the values to search the data. For example when searching for any cases where BS4 has been entered the values would be Q11=”BS4″ or Q11=”bs4″ or Q11=”Bs4″. Each variation of how BS4 could be written has been accounted for. Note: Using the word OR, or a comma (,) in the values has the same effect.
  6. Repeat steps 4 and 5 for each post/zip code you want to search for.
  7. Click on the Count responses icon Count response to see a counts for each post/zip code area in the derived variable.
  8. Click on the green tick icon to save the derived variable.

You can now use the derived variable, in the same way as any other variable, in your analysis or in a filter.

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