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Create charts
Charts are useful for giving your participants feedback and are also a way for you to have live statistics in the web interface (See Calculate chart from data). Charts can either be calculated using all participants' data or individually by only using data from one participant.
Charts that use all participants' data are publicly visible (in the app and also in the Web Interface. See Show statistics from studies). Data for these charts are collected on the server.
Individual charts are only available for participants using the Android or iOS app and are visible for them only (the researcher can also calculate individual charts in the Data section). Only data from the individual participant is used for these charts.
If you want to show a chart to participants only after they have completed the study, check the option "Only visible for participants who have finished the study". Be aware that participants who have left the study prematurely will also be able to see this chart.
Charts have a chart type, and a data type. The chart type determines how (/in which kind of chart) the data is presented.
There are four data types to choose from:
Responses for a variable are cumulated per day, and each entry on the x-axis represents one day. The "Value" setting determines if the y-axis should either display the calculated mean over a day ("Mean"), all responses from a day added together ("Sum"), or a count of the number of saved responses for a day ("Count").
The number of different responses over all variables in the graph are counted. Each entry on the x-axis represents a different response value. The y-axis shows the number of responses with this value. Checking "Count in percent" will display the values on the y-axis as percentages. When "Treat values on x-axis as number range" is checked, the values represent a series of numbers starting with the lowest number from the responses and ending with the highest number from the responses.
With this setting only one value per variable on the x-axis is created: A cumulated value over all responses. The "Value" setting determines if the y-axis should either display the calculated mean over a day ("Mean"), all responses from a day added together ("Sum"), or a count of the number of saved responses for a day ("Count"). This data type is probably only useful if more than one variable is used on the y-axis.
The responses of the x-axis variable are shown together with the respective y-axis variable. It makes only sense to compare variables that are saved together (or in quick succession. See Note below). The scatter plot is probably the best chart type choice to display this datatype properly.
Note: When the data type "Comparing on x- and y-axis" is chosen, chart data is actually cumulated into small timeslots (default 675 seconds) to save space and performance. All responses that are saved within that timeslot are treated as one entry on the x-axis or y-axis respectively.
When the number of saved timeslots becomes too great, the server will automatically increase the size of the timeslots for that value to reduce the number of entries and also issue an error report as information.
A chart can display several variables (or variable sets for the data type "Comparison on x- and y-axis"). For each variable you can also add one or multiple conditions. When saving a response, the conditions of each variable (in the response) are checked. If the outcome of the conditions is false, the data for this response will be ignored for this variable.
Note: The outcome of conditions must be fulfilled at the time, the response is recorded. Therefore, you can only check variables for the conditions that are saved at the same time as the axis variable