Quota Dialog

Quota Dialog

Quota Control lets you specify how many interviews you want to complete overall, or for certain types of respondents. Once the quota is reached, new respondents who qualify for quota cells that have already filled can be skipped to a page that tells them that the survey is full. For a review of quota control, click here.

Let's begin with the simple case where the researcher wants to limit the number of total surveys to 500 completed respondents. From the Write Questionnaire dialog, add a Quota question at a point very early on in the survey (we suggest page 1 so that respondents don't have to spend time answering questions if the quota is filled). The Quota question appears in the list of questions, but it really isn't a question in the traditional sense, since nothing is displayed on the screen and no respondent answer is required. Rather, it may be considered a Quota Qualification Point, at which SSI Web evaluates the quota logic defined in the Quota question, determines if that quota cell has been filled and assigns the respondent to a quota cell.

When you add a Quota question, the Quota dialog is displayed:

Click the Add button to add a quota cell to the table. In this first example, we've added just one quota cell (named "Completes"), where all respondents qualify for this cell (we've clicked Always qualify rather than giving specific qualification logic). The relevant information specified in the Cells tab dialog is as follows:

Value	Cell Name	Cell Limit	Qualification Logic
1	Completes	500	Always qualify

The Cell Value is a numeric value that SSI Web assigns to represent a quota cell. This is the cell's numeric code. Cell Name is a short label for describing the quota cell which can contain no spaces.

As another example, the researcher may wish to limit the survey to 500 males and 550 females, based on a previous question named Gender:

Value	Cell Name	Cell Limit	Qualification Logic
1	Males	500	Gender=1
2	Females	550	Gender=2

This is an example of mutually-exclusive qualification logic: respondents are either male or female. With SSI Web's Quota Control, it is possible to set up quota cells that are not mutually exclusive. Even if quota cell definitions are not mutually exclusive, respondents are assigned to one (and only one) quota cell. The order you enter the Quota Cells matters if the Qualification Logic is not mutually exclusive (by default, Qualification Logic is evaluated from top to bottom of the list). By default, respondents are assigned to the first quota cell for which they qualify, from top to bottom.

Quota cells can become more complex, such as a combination of Gender and Age. Also, if you do not like the default Cell Values, you can change them:

Cell Value (Code)	Cell Name	Cell Limit	Qualification Logic
101	YoungMales	250	Gender=1 AND Age=1
102	OlderMales	200	Gender=1 AND Age=2
201	YoungFemales	300	Gender=2 AND Age=1
202	OlderFemales	240	Gender=2 AND Age=2

Click Add to add new quota cells, or (after highlighting a quota cell) click Delete to delete a quota cell. The Qualification Logic rules and syntax are described in the section that follows.

Even though you have specified specific Cell Limits, it is very possible for you to exceed those limits by some (usually small) amount. For example, respondents may be entering the survey quickly, and since those who are In Progress are not counted toward the total completed records, quota control will let extra respondents into the survey before the Cell Limit has been reached. There are more sophisticated rules (Predictive Quota Control) for accounting for respondents who have passed the Qualification Point and are In Progress, and these are described in the documentation for Predictive Quota Control (Advanced tab).

Note: Changes you make to the quota control settings must be uploaded to the web server for these modifications to affect data collection. Please read the section on Changing Quota Cell Settings During Data Collection for more information.

Qualification Logic Syntax

SSI Web uses SSI Script for its qualification logic syntax (the syntax rules are the same as for skip patterns). You type this logic into the Qualification Logic text field.

Supported Logical Operators:

and

not

Supported Mathematical Operators:

=, <, >, <=, >=, <> "not equal to"

+, -

/ "division"

* "multiplication"

^ "raise to the power of"

mod "modulo"

and all other SSI Web Functions.

You can check whether the instructions (syntax) you provide are valid by clicking

. Syntax is also checked when you prepare your survey for local or remote web server.

Example Syntax

Below are some examples of valid Qualification Logic syntax. If these statements evaluate to true, then the respondent is qualified for that particular cell.

Q1 = 23 "Qualify for this cell if Q1 is equal to 23"

Q1 >= 10 " Qualify for this cell if Q1 is less than or equal to 10"

Q1 <> 99 " Qualify for this cell if Q1 is not equal to 99"

Age > 18

(Age > 18) and (Gender = 1)

(Age > 18) or (Q1 = 23) or (Q2 > 3.534)

((ageQuestion > 18) Or (Not Shown(ageQuestion))) "Shown" is a function that returns true if the question specified in the parenthesis has been seen

Q23/(Q24+Q25) >= 23.5

(Q23*Q1)^0.5 < 10 "^" means "raised to the power of"

Q1OpenEnd="hello world"