Differences

This shows you the differences between two versions of the page.

--- en:create:random_questionnaire [05.02.2015 11:23] – [Weighted Random Selection] alexander.ritter
+++ en:create:random_questionnaire [25.03.2021 20:49] (current) – [How-to] sophia.schauer
@@ 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.
+**Warning:** If you implement randomization across different questionnaires, systematic dropouts can lead to an (sometimes significantly) uneven distribution in the completed questionnaires. Use only a questionnaire with [[:en:create:randomization]] of the stimulus to reliably fill the experimental groups evenly (see also the following note).
-**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]].
+**Warning:** If the experimental groups work in different questionnaires, it is necessary to pay special attention to ensure that the questionnaires are identical except for the treatment. For example, if a change is made in only one of the questionnaires after the pretest, this can lead to confounding and the inability to use the data. The "normal" [[:en:create:randomization]] is less error-prone here.
-===== Notes =====
+**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]]).
-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//.
-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.
+===== How-to =====
-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.
+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".
-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.
+Define this questionnaire as the default questionnaire under **Assemble Questionnaire** -> **Manage Questionnaires**.
+{{:de:create:scr.random-questionnaire.questionnaires.png|Questionnaires for random selection}}
-===== Set Questionnaire as Default =====
+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".
-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.
+{{:de:create:scr.random-questionnaire.random-create.png|Create random generator}}
+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}}).
-If only one questionnaires exists in the survey project then this questionnaire will always be used as default.
+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}}
-===== Random Selection from Selected Questionnaires =====
+Open the questionnaire that you have created for random distribution under **Assemble Questionnaire** for editing.
-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.
+  - 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.
-**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.
+<code php>
+$qnr = value('RF01', 'label');
+goToQuestionnaire($qnr);
+</code>
+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.
-===== Weighted Random Selection =====
+{{:de:create:scr.random-questionnaire.questionnaire.png|Questionnaire to randomly select a questionnaire}}
-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.
+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.
-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.
+===== Weighted Selection =====
+If some questionnaires should be selected more often than others (higher weighting in the random selection), please simply enter their identifiers several times in the random generator.
+The following random generator for example would select te questionaire "control" twice as often as "order1", "order2" or "order3".
+<code>
+control
+control
+order1
+order2
+order3
+</code>
+===== Interaction with extern Panels =====
+If you recrute the respondants from an extern panel you have to transmit respondetcodes in most cases in the redirect: [[:en:survey:panels]]
+As soon as ''[[:en:create:functions:gotoquestionnaire]]'' is used, a new case is created in the dataset. In this (new) interview, it is no longer possible to access the data that were collected in the original questionnaire (here, for example, "random"). This also applies to a participation code that may have been passed via URL from the panel provider.
+For the process to work, you have to explicitly pass the participation code to the subordinate interview. Therefore the function ''[[:en:create:functions:multileveldown]]'' is used. If the participation code was passed by reference (REF), it would look like this.
+<code php>
+$qnr = value('RF01', 'label');
+multiLevelDown($qnr, reference());
+</code>
+In the subordinate questionnaire you can then access the passed code using ''[[:en:create:functions:multileveldata]]''. In the redirect, the reference would then no longer be used directly ...
+<code php>
+redirect('https://www.panelanbieter.de/complete?xyz=ABCDEF&uid=%reference%');
+// or equivalent
+redirect('https://www.panelanbieter.de/complete?xyz=ABCDEF&uid='.reference());
+</code>
+... but the data passed by ''multiLevelDown()'', i.e.
+<code php>
+redirect('https://www.panelanbieter.de/complete?xyz=ABCDEF&uid='.multiLevelData());
+</code>