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en:create:questions:random [28.07.2019 12:39] – [Application] urbanalgae | en:create:questions:random [30.07.2019 22:23] – Update admin | ||
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The random generator developed from the [[: | The random generator developed from the [[: | ||
- | The extensive examples in the chapter [[: | + | The extensive examples in the chapter [[: |
**Hint:** If the random variation doesn’t work as desired, the debug-informations in the questionnaire will provide fast explanations. (Read more at [[: | **Hint:** If the random variation doesn’t work as desired, the debug-informations in the questionnaire will provide fast explanations. (Read more at [[: | ||
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* For the second drawn ballot two kinds of values are available: first the numeric code and second the inscribed text for the ballot (e.g. the file name of a image, as seen in the example below) | * For the second drawn ballot two kinds of values are available: first the numeric code and second the inscribed text for the ballot (e.g. the file name of a image, as seen in the example below) | ||
- | |||
* The random generator can draw multiple ballots during one interview (option //Amount of ballots per interview// | * The random generator can draw multiple ballots during one interview (option //Amount of ballots per interview// | ||
+ | * The random generator yields only one value (including it’s inscription) per ballot. Combinations are only possible using the following workaround: The combination is saved as an inscription and separated after the drawing using [[http:// | ||
- | * The random generator yields only one value (including it’s inscription) per ballot. Combinations are only possible using the following workaround: The combination is saved as an inscription and separated after the drawing using [[http:// | ||
===== Example: Varying screen-stimulus ===== | ===== Example: Varying screen-stimulus ===== | ||
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===== Example: Show multiple images ===== | ===== Example: Show multiple images ===== | ||
In this example participants should rate 300 images. To achieve this each participant has to rate 20 different pictures - each on a different page. | In this example participants should rate 300 images. To achieve this each participant has to rate 20 different pictures - each on a different page. | ||
+ | |||
==== Preperation ==== | ==== Preperation ==== | ||
* Upload all images to **Images and Media Data** | * Upload all images to **Images and Media Data** | ||
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* The last Page which belongs to stimulus B receives the ID “endB”. | * The last Page which belongs to stimulus B receives the ID “endB”. | ||
* The first Page of the final part (which follows directly to “endB”) receives the ID “final”. | * The first Page of the final part (which follows directly to “endB”) receives the ID “final”. | ||
+ | |||
==== Application ==== | ==== Application ==== | ||
+ | |||
Under **Create a Questionnaire** drag and drop the random generator to the last page of the generic part. The following page should respectively have the ID „beginA“. | Under **Create a Questionnaire** drag and drop the random generator to the last page of the generic part. The following page should respectively have the ID „beginA“. | ||
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+ | ===== Readjust the Drawings ===== | ||
+ | |||
+ | If one works with many experimental groups, it is possible that the actually successful equal distribution is lost due to removals required by data cleaning. Especially if the number of cases per group is very small, the cases that have to be removed (e.g. as a result of the manipulation check) may cause a substantial tilt. Then it may be necessary to adjust the random number generator slightly during the survey. | ||
+ | |||
+ | **Warning: | ||
+ | |||
+ | **Tip:** In a situation where you can't adjust the random drawing afterwards, you can use an [[: | ||
+ | |||
+ | If the conditions for readjustment (see above) are fulfilled, the procedure is as follows: | ||
+ | |||
+ | - The preliminary data set is cleaned up (dropout, missing answers, manipulation check, no consent to the use of the data, ...). | ||
+ | - A frequency table of the random generator variable is created. | ||
+ | - This frequency table is converted into a format '' | ||
+ | - This list is drawn into the field //drawn so far// in the random generator -- the order of the values does not matter, the only important thing is that code and number are contained. | ||
+ | - After saving, the list is automatically sorted and further random draws are made in such a way that previous inequalities are compensated. | ||
+ | |||
+ | The list of codes and usable cases can look like this: | ||
+ | |||
+ | < | ||
+ | 111111: 2 | ||
+ | 111211: 1 | ||
+ | 111311: 2 | ||
+ | 111411: 2 | ||
+ | 112111: 1 | ||
+ | 112211: 2 | ||
+ | 112311: 2 | ||
+ | 112411: 2 | ||
+ | u.s.w. | ||
+ | </ | ||
+ | |||
+ | In Excel or OpenOffice Calc, such a list is created by combining the previously created frequency table (with codes, not labels) with the following function (if the codes are in column A and the frequencies are in column B): | ||
+ | |||
+ | <code excel> | ||
+ | =CONCAT(A1; ": "; B1) | ||
+ | </ | ||
+ | | ||
+ | In GNU R you can output the frequency table and the list as follows (if the variable of the random generator is e.g. RG01): | ||
+ | |||
+ | <code r> | ||
+ | tmp = table(data$RG01) | ||
+ | cat(paste(paste(names(tmp), | ||
+ | </ |