# Sampling
Warning!
If you edit anything in your sampling while your study is already running, the changes won't propagate automatically to your participants' devices.
To fetch the changes on your participants' devices, they need to follow the steps described in the chapter App usage.
# Sampling Graph
The sampling defines in a visual language when an action will be performed. With this visual language several sampling blocks can be combined to design a sampling scheme that fits nearly every study.
You can drag the blocks from the left side to the white sampling document on the right side. You can rearrange the blocks by dragging them around. You can adjust the view of the sampling document by dragging the white background.
After placing the blocks you can configure them. You can do so by double-clicking the block or clicking on the edit pen in the right top corner of the block. In the appearing window you need to configure the block. As soon as you saved the block configuration the block shows its configuration in an abbreviated version. The "Form" block only shows the internal id of the form. With the root block Sampling Running you can configure the study like the pin code or the lockout mode.
The sampling blocks can be combined in a specific order (the grammar of the visual language). This order is represented through the colors of a traffic light (red, yellow, green).
- One or more red conditions. These conditions narrow down the range of the sampling.
- One yellow trigger. This trigger defines when the actions below start.
- One or more green actions. These actions execute as soon as the trigger applies.
As soon as you have placed some blocks in the sampling document you can connect them. Do this by dragging the handle on the bottom of the block to the top of the subsequent block. The handle of the block (square or circle) assures that you only place one trigger in each path.
You can save your sampling by pressing the save button in the top right corner.
WARNING
If you leave the sampling page without saving, your changes will be lost!
# Alarm Configuration
The alarm block triggers the participant to e.g. fill out a form. In the default configuration the alarm reminds the participant over five minutes.
By changing the Sound/Vibration duration, the Display duration and the Number of alarms, you can configure how often and how long the participant will be reminded. You can also allow the participant to delay or dismiss the alarm if he is currently busy.
# Random Time Trigger
The random time trigger follows a stratified randomization instead of allowing random prompts at any possible time. It takes the set time frame and divides it equally to accommodate the number of required prompts. It’s within these smaller chunks that the random prompt appears, only governed by the minimum time between prompts.
For Example, you set the Start Time to 8:00 and the End Time to 20:00, the Number of Prompts to 6 and the Minimum Time Between Prompts to 0:30 (30 minutes). The random time trigger will now divide the 12 hour time frame between start time and end time into 6 chunks of 2 hours. So the 6 prompts appear randomly in the following time frames:
Note: If a prompt occurs near the end of its time frame, the next prompt actually falls in a smaller time frame due to the minimum time between prompts. E.g. in the example above, if the first prompt occurs at 09:50 and the minimum time between prompts is set to 0:30, the second prompt triggers sometime between 10:20 and 12:00.
WARNING
There are 2 different messages which could be displayed by the smartphone after starting a study with the random time trigger:
- Configuration warning in 'Random Time': 'Minimum Time Between Prompts' is too high to get a good random distribution.
This message will be displayed, when two times the Minimum Time Between Prompts is higher than the potential time frame. This may lead to a bad randomization. - Configuration error in 'Random Time': 'Number of Prompts' do not fit into day because of 'Minimum Time Between Prompts'.
This message will be displayed when the configured Minimum Time Between Prompts is higher than the potential time frame. This will lead to a non-functional randomization.
# Best practice
# Simple Scheme
Sampling every day between 08:00 and 20:00, 8 alarms with one form. If you have a SIM-Card and mobile data contract installed in your smartphone you can instantly upload the collected forms by adding an upload block. For simplicity we only added this block to this example.
# Simple Scheme + Participant Can Start the Form
The same scheme as before, but now the participant starts a form himself by pressing the button Start form. An alarm is not necessary if the participant triggered the form himself.
# Weekday/Weekend Sampling Scheme
In this scheme we added two weekday blocks and two fixed time blocks. From Monday to Friday, the random sampling is active. At the weekend only at the fixed time 14:00 and 18:00 o’clock an alarm comes up.
# Different Forms at Different Days
If you want to have different forms to appear at different days of the study you can use the Sampling Day blocks. In the example below the first path is only executed at day one, the second path is executed at day two.
# Different Forms at Different Times
If you want to have different forms to appear at different times you can have a different path (with an alarm block and a form block) for each time.
# Mixed Scheme
Of course you can also mix all the examples above, but we recommend keeping it as simple as possible.
# Different Start Dates for Each Participant
It is very common, that you run a study with multiple participants that start at different days. Please try to keep your sampling scheme as date independent as possible and try not to use the Date Range block. Instead just define a start and end date for each participant in the Participants tab of your study.
In the example below the sampling for the first participant starts at 2013-03-12 and ends at 2013-03-19 (both days included). The sampling for the second participant starts one day later but does not end until you stop it on the smartphone. The sampling for the third participant starts as soon as you start the sampling on the device and will only stop if you stop it on the smartphone.
# Mutable Values (a.k.a. Variables)
With mutable values the sampling scheme can be even more flexible. It is very powerful, but can also introduce errors, if the sampling scheme is not correctly designed. This feature is currently in beta, please contact us, if you want to test this feature!
- Make sure you use the movisensXS Android app version 0.6.3412 or newer.
- Go into the preferences of your study (wrench icon), select movisensXS Library v3357 or newer and save the changes.
- Go into the sampling, there are now new sampling blocks available in the Advanced tab (Check Mutable Value and Change Mutable Value).
With these two blocks it is possible to activate/deactivate different parts of your sampling in dependency of previous actions.
The following example demonstrates on how to activate a random triggering only, if a participant filled out an "Out of bed" questionnaire.
The following example demonstrates on how to activate a random triggering only, if a participant is not asleep.
The following example demonstrates on how to show a button only, if the participant has not yet completed this form today.
The following example demonstrates on how to implement a Do not Disturb button, that the participant can use if he does not want any alarms in the next hour.
# Sampling Blocks Library version 7365
Study Running
This node is active if the study is running.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Enable Messaging | Allow participant to write/receive messages to/from the study supervisor. | Boolean | true |
| Full Screen | movisensXS runs in fullscreen during the study. | Boolean | false |
| Lock other Applications | If you activate this other applications are not accessible for the participant. | Boolean | false |
| Allowed Apps On request | Specify apps that are allowed to run (e.g. 'com.yourApp'). This is required if you are using your own apps in the forms. This functionality may not work on Android 5.0 or higher. | String | com.yourApp |
| Not Allowed Apps On request | Specify apps that are not allowed to run (e.g. 'com.yourApp'). | String | |
| PIN code | This pin code allows the supervisor to control the study. The pin code '0' enables accessing the study control without pin. | Integer | 2486 |
| Log Node Status and Variables On request | Logging of node status changes into the unisens file format under /sdcard/movisensXS/logs/ | Boolean | false |
| Mutable Value Editor On request | Enables mutable value editor which is accessible via study management screen. | Boolean | false |
| Form Starter On request | Enables form starter which is accessible via study management screen. | Boolean | false |
| Disable home screen On request | Disables the home screen from showing. Only necessary if movisensXS is used to trigger actions in the background. | Boolean | false |
Advanced
Change Mutable Value On request
This action can change a mutable value.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Mutable Value On request | Name of the mutable value | String | Counter |
| Operation On request | Operation to perform (set, increment, decrement) | String | increment |
| Value On request | Value of the operation (If operation='set' the mutable value is changed to this value. If operation='increment/decrement' the variable is changed by this amount). | String | 1 |
Check Mutable Value Action On request
This action can check a mutable value and blocks following nodes if defined condition not applies.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Mutable Value On request | Name of the Mutable Value. [Predefined Mutable Values are SamplingDay, SamplingNumber] | String | Counter |
| Comparison Operator On request | Comparison operators between Mutable Value and Compare Value, e.g. is true if Mutable Value is 'greater' than Compare Value (equal, unequal, greater, less) | String | equal |
| Compare Value On request | Value to compare the mutable value to (Not case sensitive). | String | 1 |
Check Mutable Value On request
This condition is true if the mutable value is equal to the compare value.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Mutable Value On request | Name of the Mutable Value. [Predefined Mutable Values are SamplingDay, SamplingNumber] | String | Counter |
| Comparison Operator On request | Comparison operators between Mutable Value and Compare Value, e.g. is true if Mutable Value is 'greater' than Compare Value (equal, unequal, greater, less) | String | equal |
| Compare Value On request | Value to compare the mutable value to (Not case sensitive). | String | 1 |
Delay
This event delays the previous event for the specified time and then triggers the successor nodes.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Delay | Time to delay the source signal in seconds | Integer | 10 |
Frequency Limit On request
This action prevents too much triggers.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Time between triggers On request | Minimal time between triggers in seconds | Integer | 3600 |
Context
App Used On request
This trigger fires if the specified app or activity is opened/closed. This functionality may not work on Android 5.0 or higher.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Type On request | Defines if triggers on open or close of the application (AppOpened, AppClosed). | String | AppClosed |
| Package or activity identifier On request | The identifier of an app (e.g. com.android.settings) or of an activity (e.g. com.android.settings/.Settings) to trigger on. | String | com.android.settings/.Settings |
Nearby Devices Condition On request
This condition will be true when at least one matching beacon is in range. It will send a bluetooth advertisement through IBeacon standard on supported devices and will take all other devices which are broadcasting with a beacon standard into account.
An IBeacon consists of three parts:
| ID | Description | movisensXS broadcast content |
|---|---|---|
| ID1 | UUID | 7ab97c36-b634-11e6-80f5-76304dec7eb7 |
| ID2 | Major value | StudyId |
| ID3 | Minor value | ParticipantID |
7ab97c36-b634-11e6-80f5-76304dec7eb7 and uses the StudyId as the Major value and the ParticipantID as the Minor value. This feature can e.g. be used to identify situations where partners are close to each other by specifying the movisensXS UUID in ID1, the StudyID in ID2 and the ParticipantID of e.g. participant 1 in the ID3 field of participant 2. You find the StudyId in the browser url of movisensXS e.g. https://xs.movisens.com/studies/111. This block is typically used in conjunction with the Log Nearby Devices mobile sensing block to log the nearby devices seen.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Broadcast Signal On request | Enable to broadcast nearby signal. | Boolean | true |
| Scanning interval On request | Determines how long the scan should last. Beacon scanning consumes power, a practical value is 10 seconds. | Integer | 10 |
| Time Between Scans On request | Interval between scans if a beacon is around in seconds. Beacon scanning consumes power, a practical value is 300 seconds. | Integer | 300 |
| ID1/URL Regex On request | Regex of ID1 or URL in case of Eddystone URL | String | [0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12} |
| ID2 Regex On request | Regex of ID2 | String | .* |
| ID3 Regex On request | Regex of ID3 | String | .* |
Geofence Trigger On request
This event fires if a given geofence was entered, left or the participant is staying in it over some time.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Latitude On request | Latitude of the geofence. | Double | 0 |
| Longitude On request | Longitude of the geofence. | Double | 0 |
| Radius On request | Radius of the given geofence in meter. | Integer | 100 |
| Geofence Type On request | Specifies if the trigger will be triggered by entering, leaving or staying in the bounds of the geofence. Options [Enter, Stay, Exit]. | String | Enter |
| Duration of Stay On request | Specifies how long the participant must stay in the geofence in seconds to trigger it. Only needed if the geofence type is 'Stay'. | Integer | 300 |
| Initial Trigger On request | Specifies if the geofence should trigger the initial location of the participant dependent on the geofence. | Boolean | false |
GIS Trigger On request
This trigger fires if the GIS returns a trigger.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| GIS url On request | GIS url | String | |
| Distance On request | Distance the device must travel to check the GIS. Distance in meters. | Integer | 100 |
Location Changed On request
This trigger fires if the location changed.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Distance On request | Distance the device must travel to trigger a location change. Distance in meters. Accuracy varies between 10 and 1000 meters. | Integer | 1000 |
Multi Geofence Trigger On request
This event fires if a given geofence was entered, left or the participant is staying in it over some time.
id,name,latitude,longitude,radius,mode,durationOfStay 0,Mensa,49.0118868,8.4168792,100,enter 1,Oxford,49.0098936,8.4144250,100,stay 2,Studierendenwerk,49.01136560000001,8.4172656,100,exit 3,Fachschaft Informatik,49.0143397,8.4178346,100,stay,600
- id integer value which should be ascending. No duplicates allowed.
- name or description of the geofence in alphanumerical characters.
- latitude latitude of the geofence. Ranges between -90 and 90.
- longitude longitude of the geofence. Ranges between -180 and 180.
- radius integervalue in meter.
- modus one of stay, enter or exit.
- durationOfStay integer value in seconds(optional, default=300).
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Geofences (CSV) On request | Geofences in a CSV format ('id,name,latitude,longitude,radius,mode,durationOfStay'). The mode requires one of 'stay', 'enter' or 'exit'. | String |
Notification Trigger On request
Trigger when a notification arrives. Please note: Notifications arrive very often, keep in mind to not bother your participants to often.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Filter On request | Only react to the given packages (Separated with ';') | String | com.whatsapp |
Location Accuracy On request
This action changes the location accuracy.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Accuracy On request | Requested Accuracy (Auto, High, Passive) | String | Auto |
Deprecated
SensorTrigger: Sensor Disconnected On request
Triggers when the coupled sensor of the 'Sensor Trigger' was disconnected from the smartphone.
SensorTrigger: Sensor Stopped On request
Triggers when the coupled sensor of the 'Sensor Trigger' was stopped.
SensorTrigger: Stop Sensor On request
This action stops the coupled sensor of the 'Sensor Trigger'
SensorTrigger: Trigger On request
Triggers when the 'Sensor Trigger' triggers.
Development
Send Intent On request
This action executes an android intent operation. An Android intent is an abstract description of an operation to be performed.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Action On request | The general action to be performed, such as 'android.intent.action.VIEW'. | String | com.yourApp.YourReceiverName |
| Data On request | The data to operate on, such as a web url. | String | |
| Type On request | The type of intent [App, Activity, Broadcast, StartSerice or StopService]. | String | Broadcast |
Intent Received On request
This condition listens to an android broadcast intent operation.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Intent On request | An Android broadcast intent is an abstract description of an operation to listen on. | String | com.yourApp.YourBroadcastName |
Forms
Alarm
This notifies the participant about a task he has to perform e.g. fill out a form.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Title | Title text of the alarm. | String | Alarm |
| Sound/Vibration duration | How long the sound and vibration lasts per alarm in seconds. | Integer | 10 |
| Display duration | How long one alarm will be shown after sound and vibration in seconds. | Integer | 50 |
| Number of alarms | How often a alarm shows. | Integer | 5 |
| Maximum delay time | How long the participant can delay the alarm in minutes (0=disabled). | Integer | 20 |
| Dismissable | The participant can dismiss the alarm. | Boolean | true |
Form
This action runs the specified form. Place an alarm before to notifiy the participant about the form!
More information about randomization and page indicators can be found here
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Form ID | Id of the form to run | String | |
| Timeout Interval | After how many seconds of inactivity a timeout warning will be shown. (0 = disable) | Integer | 60 |
| Timeout Length | Length of the timeout alarm in seconds. | Integer | 20 |
| Display back button | Allows the user to go back to the previous question. | Boolean | true |
| Show Page Indicator | Shows a small page indicator at the top of the form. | Boolean | true |
| Screen orientation | Locks the screen orientation [Free, Portrait, Landscape]. | String | Free |
| Randomized On request | If marked, the questions are displayed in a random order. | Boolean | false |
| Include Form to Gamification On request | If marked, the the completions or incompletions will be used in gamification score calculation. | Boolean | true |
| Count of random items On request | Shows only the given count of all items in a stratified randomized order (if randomized is activated). If 0 all items will be randomized. | Integer | 0 |
Upload Results
This action uploads the collected results to the server.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Automatic upload retry | Retry upload automatically if no internet connection was available. WARNING: All upload blocks will automatically using the highest choosen option. Please don't mix Wlan and Any (None will be ignored in the future). Options [None, Wlan, Any] | String | Wlan |
Logging
Record Audio On request
This action records the audio of the microphone for the specified duration. Files are stored on the sdcard in the folder 'movisensXS/EAR'. Please Note: If you use this, you shouldn't use other item formats which connect to the microphone (video, audio).
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Duration On request | Time to record audio in seconds | Integer | 45 |
| Uncompressed On request | The files are saved as uncompressed .wav foles | Boolean | false |
Smartphone
Battery Low On request
This condition is true if the battery level is below the configured level.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Level On request | The low battery level. | Integer | 20 |
Study
Number of Responses On request
This condition is true if the number of responses are in the defined range (Response number starts with 0 and increments if a form is completed).
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Minimum responses | Minimum responses to be true | Integer | 0 |
| Maximum responses | Maximum responses to be true | Integer | 50 |
Button pressed
This event fires if the participant presses a presented button and triggers the successor nodes. A.k.a. Event-contingent.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Button label | Label of the button that is shown in the home screen | String | Start form |
| Button order | The order of the buttons on the home screen. The higher the order/weight, the deeper it sinks. | Integer | 1 |
| One time button | If you activate this the button is only once clickable. | Boolean | false |
| Button Group On request | Button will be added to the defined button group and can be minimized. | String |
Time
Date Range
This condition is true if the current date is in the selected range. Start and end date is included.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Start date | Start date of the condition. Dates must be formatted as yyyy-MM-dd | Date | |
| End date | End date of the condition. Dates must be formatted as yyyy-MM-dd | Date |
Fixed Time
This event fires if the specified time is reached and triggers the successor nodes. A.k.a. Interval-contingent.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Time | Time in the format HH:mm | Date | 14:00 |
Immediately
This event fires as soon as the previous node is true.
Initial
This event fires only once after the previous node is true.
Participant Time Trigger On request
This event fires if the time of the mutable value is reached and triggers the successor nodes. The mutable value can be set by the participant with the time item format in a form.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Mutable Value On request | Name of the Mutable Value. | String | Time_1 |
| Repeated On request | Trigger should be repeated every day. | Boolean | true |
Random Time
This event fires randomly a specified number of prompts in the specified time period and triggers the successor nodes. A.k.a. Signal-contingent.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Start Time | Time in the format HH:mm | Date | 08:00 |
| End Time | Time in the format HH:mm | Date | 20:00 |
| Mutable Value Name for Start Time On request | Name of mutable value which defines the start time. | String | |
| Mutable Value Name for End Time On request | Name of mutable value which defines the end time. | String | |
| Number of Prompts | Number of Prompts between start and end time | Integer | 8 |
| Minimum Time Between Prompts | Time in the format HH:mm | Date | 00:30 |
Repeated
This trigger fires in the configured interval as long as the previous condition stays true.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Repeat interval | Interval to trigger in seconds. 3600 = 1 hour. | Integer | 3600 |
| Reset time, when other triggers happen On request | When enabled, the interval time is reset, if another trigger happened during the interval time. | Boolean | false |
| Randomization time On request | Time to randomize the repeat interval in seconds. e.g. 600 = ±10 minutes. | Integer | 0 |
Sampling Day
This condition is true if the sampling day is in the defined range (Sampling day starts with day 1 and increments at midnight if sampling is running).
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Start day | Start day as number | Integer | 1 |
| End day | End day as number | Integer | 2 |
Time Range
This condition is true if the current time is between the specified time range.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Start Time | Time in the format HH:mm | Date | 08:00 |
| End Time | Time in the format HH:mm | Date | 20:00 |
| Mutable Value Name for Start Time On request | Name of mutable value which defines the start time. | String | |
| Mutable Value Name for End Time On request | Name of mutable value which defines the end time. | String |
Weekday
This condition is true if the enabled weekday is reached.
| Label | Description | Type | Default-Value |
|---|---|---|---|
| Weekdays | Comma-seperated list of enabled weekdays. [Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday] | String | Monday, Tuesday |
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