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--- en:create:random_questionnaire [05.02.2015 11:23] – [Weighted Random Selection] alexander.ritter
+++ en:create:random_questionnaire [30.07.2019 20:46] – admin
@@ Line 1: / Line 1: @@
 ====== Random Selection for Questionnaires ======
-Multiple questionnaires can be created in one survey project (**Compose Questionnaire** -> //Further questionnaires// tab). If the participant calls up the [[:en:survey:url|URL to the Questionnaire]], it can be randomly assigned to one of the questionnaires. There are options explained at the bottom in **Compose Questionnaire** -> //Further questionnaires// tab -> //Random Selection for Questionnaires// which can be selected in order to achieve this.
+In a survey project you can create several questionnaires (**Assemble Questionnaire**) -> **Create new Questionnaire** or **Manage Questionnaires**). If the participant opens the [[:en:survey:url|link to to questionnaire]], they can be randomly assigned to one of the questionnaires.
+**Note:** For experiments it is usually much easier (!) to create only one questionnaire and vary the stimulus with a small PHP code ([[:en:create:randomization]]).
-**Note:** Random selection of questionnaires has some restrictions (see notes below) and this option is __only__ sensible __in a few__ exceptional cases. As a rule, it makes much more sense to use normal [[randomization|randomization]].
-===== Notes =====
+==== How-to ====
-Selection or random selection takes place every time the project folder is selected without a specific questionnaire being specified ([[:en:survey:url]]). This address (URL) is found under **Survey Project** -> **Project Settings** -> //Project folder//.
+First you create an additional questionnaire under **Assemble Questionnaire** -> **Create new Questionnaire**, that takes care of the random assignment. The questionnaire identifier can be chosen freely, for the following description we use the ID "random".
-In an unrestricted random selection, the different conditions will usually usually drawn an unequal (!) number of times. If 100 people are spread across 5 groups, the groups could be distributed as follows: 32, 7, 13, 28, 20. The larger the subgroups, the more unlikely (not impossible!) there will be disproportional variations. If groups of the same size are required, a [[random_urns|randomization with urns]] within a questionnaire is the method of choice.
+Define this questionnaire as the default questionnaire under **Assemble Questionnaire** -> **Manage Questionnaires**.
-The same goes for a weighted random selection: as a rule, approximation to the desired distribution only occurs in the region of larger numbers (n > 1000). Statistical outliers are therefore not possible either.
+{{:de:create:scr.random-questionnaire.questionnaires.png|Questionnaires for random selection}}
-The questionnaire a participant fills in is always noted in the variable ''QUESTNNR'' ([[:en:results:variables]]) in the data record. This applies to the explicit selection of the questionnaire in the link, just like the random selection of a questionnaire.
+To ensure an equal distribution of the participants on the questionnaires, you need a question of the type [[:en:create:questions:random]]. You can create this question in any category -- for the further description it is assumed that this question has the ID "RF01".
+{{:de:create:scr.random-questionnaire.random-create.png|Create random generator}}
-===== Set Questionnaire as Default =====
+Enter the IDs of the questionnaires (see above) you want to choose between as //codes// in the random generator and save the question ({:button.save.png|Save question}}).
-One of the questionnaires will be used as default if this option is chosen. The link to the survey project will then always lead to the same questionnaire - except when another questionnaire is explicitly specified in the link.
+Leave the default setting "equally distributes" selected for the //type of drawing//. The option "Equally distributed in finished questionnaires" will //not// work because the random distribution questionnaire will never be finished.
+{{:de:create:scr.random-questionnaire.random-contents.png|Random generator for the selection of the questionnaire}}
-If only one questionnaires exists in the survey project then this questionnaire will always be used as default.
+Open the questionnaire that you have created for random distribution under **Assemble Questionnaire** for editing.
+  - Drag the random generator (RF01) to the first (and only) page of the questionnaire, and
+  - place the following [[:en:create:php|PHP code]] below it.
-===== Random Selection from Selected Questionnaires =====
+<code php>
+$qnr = value('RF01', 'label');
+goToQuestionnaire($qnr);
+</code>
-One or more questionnaires can be selected with this option. If the URL is called up without a questionnaire being specified (see above), this means one of the selected questionnaires will be chosen at random.
+The function ''[[:en:create:functions:value]]'' retrieves the ID of the randomly drawn questionnaire from the random generator. The function [[:de:create:functions:goToQuestionnaire]] jumps directly to the questionnaire with the corresponding ID.
-**Note:** As a rule, an unrestricted random selection results in questionnaires being called up different numbers of times. Therefore, please take the information above into consideration.
-===== Weighted Random Selection =====
-Weighted random selection represents an extension of a random selection. The principle is the same as a random selection: one of the questionnaires from those with specified weighting (i.e. not 0) will be selected at random.
-Questionnaires with a higher weighting are therefore chosen with a correspondingly higher probability. The specific numbers that are input is not important, what matters is the relation: a questionnaire with a weighting of 2 will be (for example) selected twice as often as one with a weighting of 1. A questionnaire with a weighting off 66 will be selected twice as often as a questionnaire with a weighting of 33.
+{{:de:create:scr.random-questionnaire.questionnaire.png|Questionnaire to randomly select a questionnaire}}
+You have chosen the questionnaire "random" under **Assemble Questionnaire** -> **Administer Questionnaires** as the default questionnaire for the survey project. The participants can call [[:en:survey:url]] without further parameters (''q=...''). They will then first be taken to the "random" questionnaire and from there randomly distributed to one of the other two questionnaires.