System Variables Table

All system variables are listed below with an explanation, but they are also shown in the main variable menu. Clicking on a variable will open a menu to the right of the screen with data type information and a short description. They can be sorted in the menu according to user preference.

Variable Name	Data Type	Description
Subject_Nr	Numeric	Subject_Nr is a global counter of participants in a study. This can be used to do custom between-subject randomization and to infer the overall number of participants in a study.
Trial_Nr	Numeric	Trial_Nr holds the current value of the trial number for the current task. This can be used to infer whether the participant is currently performing the first, second, third, (and so on) trial in this task.
Trial_Id	Numeric	Trial_Id holds the current value of the trial id for the current task. This can be used to infer which trial is currently being performed by the participant.
Condition Id	Numeric	Condition_Id holds the current value of the condition id for the current trial. This can be used to infer which condition is currently being performed by the participant.
Subject_Code	String	Subject_Code is a unique string for each subject / session across all experiments running on Labvanced. This can be used to uniquely identify each participant or session.
Group_Name	String	Group_Name holds the value of the subject group name for each participant. This can be used to infer to which subject group each participant is assigned to.
Session_Start_Time	Date	Session_Start_Time records the start date and time of the current participant session in the participant's local time, specifying their UTC time zone.
Session_End_Time	Date	Session_End_Time records the end date and time of the current participant session in the participant's local time, specifying their UTC time zone.
Session_Name	String	Session_Name holds the value of the session name for the current session. This can be used to infer which session is currently being performed by the participant.
Session_Nr	Numeric	Session_Nr holds the current value of the session number for the current session. This can be used to infer whether the participant is currently performing the first, second, third, (and so on) session.
Block_Name	String	Block_Name holds the current value of the block name for the current session. This can be used to infer which block is currently being performed by the participant.
Block_Nr	Numeric	Bock_Nr holds the current value of the block number for the current session. This can be used to infer whether the participant is currently performing the first, second, third, (and so on) block in this session.
Task_Name	String	Task_Name holds the current value of the task name for the current block. This can be used to infer which task is currently being performed by the participant.
Task_Nr	Numeric	Task_Nr holds the current value of the task number for the current block. This can be used to infer whether the participant is currently performing the first, second, third, (and so on) task in this block.
TimeMeasure_Mean	Numeric	TimeMeasure_Mean provides an estimate of how precisely reaction times can be measured by the participants computer/device. The provided value is a mean offset of several reaction time measurements in milliseconds. It can be used to infer how precisely stimuli were shown on the screen.
TimeMeasure_Std	Numeric	TimeMeasure_Std provides an estimate of how reliable/consistent reaction time measurement is throughout the experiment. The provided value is a standard deviation of several reaction time measurements in milliseconds. It can be used to infer how comparable reaction time measurements are across trials and conditions.
Crowdsourcing_Code	String	Crowdsourcing_Code holds the value of the unique crowdsourcing code, typically shown to the subject at end of the experiment to complete the crowdsourcing session and claim the payment.
Crowdsourcing_SubjId	String	Crowdsourcing_SubjId holds the value of the unique identification code for each crowdsourcing participant. This can be used to later on create a reference between crowdsourcing data on Labvanced and the external crowdsourcing service (e.g Mechanical Turk).
Subject_Nr_Per_Group	Numeric	Subject_Nr_Per_Group is a counter per subject group in a study. This can be used to do custom between-subject randomization and to infer the current number of participants within each subject group.
Role_Id	Numeric	Role_ID is used for multi user/multi participant studies to refer uniquely to one of the participants of the study. This can be used to present different frames and roles to different participants within the same task/experiment.
Multi_User_Group_ID	Numeric	Holds a unique group ID for multi-user studies. This helps researchers identify which subjects participated in a group together.
Displayed_Language	String	Displayed Language holds the value of the selected display language (if there were 2 or more languages to select from). This value can be used to show different content, i.e. texts for different language settings.
Window_Width_In_Pixels	Numeric	Holds the value of the participant's browser window width in pixels.
Window_Height_In_Pixels	Numeric	Holds the value of the participant's browser window height in pixels.
Screen_Width_In_Pixels	Numeric	Holds the value of the participant's screen width in pixels.
Screen_Height_In_Pixels	Numeric	Holds the value of the participant's screen height in pixels.
Pixel_Density_PerMM	Numeric	The number of pixels in 1 millimeter of the participant's screen. Helps researchers infer the physical size of the participant's screen.
Experiment_Version	Numeric	A counter that increases each time the experiment is saved. Denotes the version of the experiment that is being edited.
Distance_To_Screen_In_CM	Numeric	The value of the distance from the participant to their device's screen in centimeters. Obtained during eye/headtracking calibration.
Browser_Spec	String	Browser_Spec holds the value of the browser used by the participant to perform the experiment. This can be used to later analyze possible differences between browsers. Allowing/forbidding certain browsers can be done via the study settings.
System_Spec	String	System_Spec holds the value of the operating system/device used by the participant to perform the experiment. This can be used to later analyze possible differences between operating systems/devices. Allowing/forbidding certain operating systems/devices can be done via the study settings.
Agent_Spec	String	Agent_Spec holds the complete String of the User-Agent-Browser-Specification. This can be used to get more detailed information about the participant's system specifications.
BrowserVersion_Spec	Numeric	BrowserVersion_Spec holds the value of the browser version used by the participant to perform the experiment. This can be used to later analyze possible differences between browser versions.
Is_Fullscreen	Boolean	A true/false indication of if the experiment is currently being viewed in fullscreen mode. Can change throughout the course of the experiment.
Always_Fullscreen	Boolean	A boolean value that is true as long as the participant keeps the experiment running in fullscreen mode. This can be used to pause/quit the experiment when a participant leaves fullscreen mode.
SelectedAge	Numeric	A numeric variable that holds the value of the age selected during the pre-study questionnaire. Does not populate if age is not one of the required values in the questionnaire.
SelectedLocation	String	A string variable that holds the value of the location selected during the pre-study questionnaire. Does not populate if location is not one of the required values in the questionnaire.
SelectedLanguage	String	A string variable that holds the value of the language selected during the pre-study questionnaire. Does not populate if language is not one of the required values in the questionnaire.
Group_Nr	String	Holds the value of the "subject group nr" for each participant. This can be used to infer to which subject group each participant is assigned to.
Completed	String	Holds the information of whether the data recording was successfully completed or not.