Block Randomization allows you to group pages of your survey into blocks, and then add logic to rotate, flip, or randomize the blocks. You can also add logic to the pages within a single block. This minimizes order bias in your survey.
To use Block Randomization:
A block is a group of consecutive pages in your survey. You can create up to 300 blocks in your survey.
To create blocks:
Block names indicate the range of pages included in the block. For example, a block containing Page 4, Page 5, Page 6, and Page 7 of your survey would be named Block: P4-P7.
To edit a block:
You can add Block Logic to control the order in which the blocks, or pages within a block, are presented to the respondent. There are two ways to apply Block Logic:
|Across multiple blocks
|Apply randomization logic to the blocks themselves, or a subset of blocks.
You can also set a limit on the number of blocks that will be shown to a respondent.
|Within a single block
|Apply randomization logic to the pages within a single block.
You can apply both types of Block Logic to a survey.
Block Randomization is commonly used for concept testing. Let's say you're testing three different advertisements. You'll need to create three blocks of pages, one for each ad.
To show each respondent all three blocks in a random order, add logic to randomize all the blocks in the survey. All respondents will see Page 1 first and Page 8 last, and they'll see the blocks in a random order.
To show each respondent only one random block, first add logic to randomize all the blocks in the survey. Then, limit the number of blocks to display to 1. Respondents will see Page 1, then one random block selected from Block 1 OR Block 2 OR Block 3, then Page 8.
How It Works with Block Randomization
|You can use Question Skip Logic or Page Skip Logic to skip respondents out of a block and to the end of the survey, disqualification page, or a future page in your survey—as long as that page doesn't belong to a block, or have Page Randomization applied to it.
|You can use Advanced Branching to skip respondents out of a block and to the next available block in the survey.
You can't apply Page Randomization to any pages contained within a block—that logic option will be disabled for pages within a block. Instead, you can randomize the pages within a single block in the Block Randomization feature to achieve the same result.
|You can apply Question Randomization to pages within blocks.
|You can't apply Carry Forward logic to questions within blocks.
When you send a survey with Block Randomization, you can see the order in which each respondent saw the pages in your survey by exporting the results in XLS format.
To export the page order per respondent:
Column A in the PageOrder.xls spreadsheet contains the Respondent ID, which you can match to the Respondent ID in the spreadsheet containing your survey results.
Column B contains the page number of the first page of the survey the respondent saw, Column C contains the page number of the second page of the survey the respondent saw, and so on.