Filters allow you to view only a portion of your survey responses at a time. Each filter is constructed out of a set of conditions that determine which responses to view and which to exclude. For example, you can set up a filter to view only those responses received before a specific date and time. Or you could set up a filter to view only those responses that answered "Yes" to a given question.
When you set up a filter, you'll be asked to select the conditions. There are two types of conditions: those based on Survey Parameters and those based on Questions.
Conditions based on Survey Parameters are not connected to a specific question. They allow you to filter out results that don't match several different conditions, such as the date and time when the survey was completed, whether or not a valid email address was provided and whether or not the survey was fully completed. This allows you to filter out results that may have been submitted too late, or results that don't contain all the information you need.
You can also choose a Question as a condition. Each question type will have an initial condition asking whether or not the respondent filled out the question. This allows you to filter out all responses that did not answer this question. But for most question types you can refine your filter even more. Set the condition to "Respondent Answered Question" and you'll see new condition options, allowing you to filter out results depending on the respondents answer to specific parts of each question.
You can set up multiple conditions in a single filter. If you prefer, however, you can also set up multiple filters and turn on only those filters you want at a given time. You can also save filters so that you can return to analyze your results later.