What types of plausibility checks are available by default?

Predefined Plausibility Checks (Plausibility Check Types)

Type	Parameter	Properties
Range check	Variable, “int” from, “int” to	Checks whether the value of the variable is a number between two values.
E-mail address check	Variable	Checks whether the value of the variable is a valid email address. It will be checked for characters used, for the “@” character and for the period before the domain address.
Standard check	Freely definable	Checks one or more variables using an operator.
Format check	Variable, format	Checks a variable using predefined regular expressions (numbers only, letters only, etc.).
RegEx check	Variable, regular expression	Checks a variable using a freely definable RegEx.
NoRegEx check	Variable, regular expression	Checks a variable using a freely definable RegEx. Returns “true” if the expression was not successful.
OnlyNumbers check	Variable	Checks whether a variable contains only numbers, comma and period.
Range check old	Variable, “int” from, “int” to	Checks whether the value of the variable is a number outside the range between two values.
Combination check	Variable, “int”	For questions with multiple response lists, checks whether the required number of checkboxes has been ticked.
Combination check (range)	Variable, “int” from, “int” to	For questions with multiple response lists, checks whether the number of checkboxes ticked is within a preset range.

Range check
The range check checks whether the number entered by the survey participant is within the number range you set. Otherwise, the plausibility check will be triggered and report an error. For this, the preset limits are included in the permissible range of values. The check also works with negative numbers.

If you set up a range check to do a JavaScript plausibility check or a combined PHP plausibility check, please note: JavaScript gives a value of “0” to an empty string (nothing entered). That is, if a respondent enters nothing, it will not be seen as an incorrect entry, rather it will be given a value of “0”, which is either permitted or prohibited depending on how each area is defined. In order to prevent this kind of misevaluation, please run a separate OnlyNumbers check (do not use AND conjunctions with the Range check) on the input field.

E-Mail address check
The e-mail address check checks the variable to be set for a correctly entered e-mail address. A correct e-mail address consists of four parts.

Example: tester@email.de

An individual user name (tester in the example).
The @ character.
A domain name (email in the example).
A country ID, separated from the domain name by a period (.de in the example). The e-mail address check checks the four parts for the following form:
The individual user name: The individual user name may contain letters and numbers as well as the characters “.”, “_” and “–”. Umlauts are not allowed.
The domain name: The domain name may contain letters, numbers and periods. Umlauts are not allowed. The domain name can be subdivided by any number of periods.
The country ID: The domain name may only contain letters, with a minimum of 2 and a maximum of 6 letters allowed. Umlauts are not allowed.

Standard check
The standard check checks the variable to be set to see whether it meets a condition set through the mathematical operators (= , < , > , <= , >= , !=).

Select the variable you want to check.
Select the mathematical operator you want to use to check the variable.
Enter the value of the variable for which the check is to be performed.

Format check
The format check checks the variable to be set to see whether it complies with a format, also set by you.
You have the choice of the following formats:

Checking to see whether the field contains no numbers.
Checking to see whether the field contains only uppercase letters.
Checking to see whether the field contains only lowercase letters.
Checking to see whether the field contains only numbers with periods or commas.
Checking to see whether the field contains only numbers with or without periods.
Checking to see whether the field contains only numbers with or without commas.

If you set up a range check to do a JavaScript plausibility check or a combined PHP plausibility check, please note: JavaScript gives a value of “0” to an empty string (nothing entered). That is, if a respondent enters nothing, it will not be seen as an incorrect entry, rather it will be given a value of “0”, which is either permitted or prohibited depending on how each area is defined. In order to prevent this kind of misevaluation, please run a separate OnlyNumbers check (do not use AND conjunctions with the Range check) on the input field.

To create the format check, please proceed as follows:

Select the variable you want to check.
Select the format for which you want to check the variable you previously set.

RegEx check and NoRegEx check
The RegEx and NoRegEx checks check the variable to be set to see whether it complies with a regular expression, also set by you.

Regular expressions are defined as follows:

Regular expressions, or RegEx for short, are used to check strings. They are used very frequently, especially in the UNIX environment, and make it easier to check strings containing many conditions.
There are to possible types of RegEx:

– RegEx check

– NoRegEx check

If a RegEx check returns “true”, an error message is output. The logic of the NoRegEx check is exactly the other way around.
RegEx checks are enclosed in “/”. Optionally, a so-called pattern modifier can be placed at the end. Please note that RegEx checks in PHP and JS may show a differing behavior. For JS checks, the results might even differ among various browsers. Because of the complexity of regular expressions, we recommend testing the check in the system first.
Examples:

– Zip code check => /^[0-9]{5}$/ (exactly 5 digits)

– Money field => /^[0-9]+ (EUR|USD)$/ (as many numbers as required + currency, either EUR or USD)

References: http://www.php.net/manual/en/ref.pcre.php

Complications can arise when, in a survey that is encoded in UTF-8 RegEx checks with JavaScript or JavaScript and PHP are carried out in order to compare strings containing more than just numbers: JavaScript is unable to recognize umlauts or other special characters that are reproduced in UTF-8 as doublebyte character (thus takes up two characters).

To create a RegEx check, please proceed as follows:

Select the variable you want to check.
In the text field, specify the regular expression whose entry is to trigger the RegEx check.

To create a NoRegEx check, please proceed as follows:

Select the variable you want to check.
In the text field, specify the regular expression whose entry is not supposed to trigger the NoRegEx check. For all entries of other types in the field to be checked, the check will be triggered.

Range check old
In contrast to the range check explained above, the range check old checks the invalid range of the variable to be set. This means that the value entered by the participant must be outside the number range you set. Otherwise, the plausibility check will be triggered.

Combination check and combination check (range)
Two other plausibility checks are available for questions with multiple response lists (question types 121, 122, 362, 521, 522, 621):

The combination check allows you to check whether a respondent has ticked a required number of checkboxes.
The combination check (range) checks whether the number of checkboxes ticked is within a preset range.