Study Sequence
Once you have defined the components you want to be part of your study, you need to tell reVISit what order to show the components in. This is done by defining a sequence object in the reVISit Spec, which has a variety of powerful options for different randomization types, as well as attention checks, breaks, and advanced skip logic for more complex studies.
ReVISit also always injects a special end component at the very end of the study, at which point the data is uploaded and the participant is instructed that they can safely close the window. Other blocks can also optionally be given id, which can then be used to jump to them.
Simple Sequence
If your study has a set order, creating a sequence is simple. Define the components in the order you want to see them, and set your order to fixed
sequence: {
order: 'fixed'
components: [
'introduction',
'consent',
'trial1',
'trial2',
'post-survey'
],
}
Nested Sequence
Many studies need to randomize the order of some of the components, but not all. You may want every participant to see introduction and consent first, but then randomize the order they see trials in. To do this, sequences can be nested. Create another object around your trials, and change the order to random.
sequence: {
order: 'fixed',
components: [
'introduction',
'consent',
{
order: 'random',
components: [
'trial1',
'trial2',
]
},
'post-survey'
]
}
In this case all participants will first see introduction and consent, and then randomly either trial1 or trial2 first, and then the other trial second, followed by the post-survey for everyone.
Studies can be nested to arbitrary depths. A frequent use case is a within subjects study where you want to randomize the order a participant sees two conditions in, and then also randomize the order of the trials within each condition. That would look like the following.
sequence: {
order: 'fixed',
components: [
'introduction',
'consent',
{
order: 'random',
components: [
{
order: 'random',
components: [
'ConditionA-1',
'ConditionA-2',
]
},
{
order: 'random',
components: [
'ConditionB-1',
'ConditionB-2',
]
},
]
},
'post-survey'
]
}
Latin Square
Studies frequently want portions of their trials to be random, but also want to ensure that their trials are not susceptible to ordering effects due to bad luck in the randomization process. A latin square study design is commonly used to combat this, and we have latin squares as a built-in option for randomization. Just change the order to latinSquare.
sequence: {
order: 'fixed',
components: [
'introduction',
'consent',
{
order: 'latinSquare',
components: [
'trial1',
'trial2',
]
},
'post-survey'
]
}
This option will create a latin square for any block using one behind the scenes, iterate through the latin square as new participants request sequences, and refill it when empty.
To further ensure consistency in the latin square, participants may be rejected via the data dashboard. When a participant is rejected, their data gets flagged (but not deleted), and the sequence they had is returned to the sequence pool. This ensures that participants that start a study but do not complete it or are stopped before completing it (failed attention check, refused consent form, etc) do not use up a row of any generated latinSquares.
Dynamic Blocks
Some studies require knowledge of the participant's responses to previous questions to determine the next component that is shown. For example, if a participant answers a question incorrectly, they may be shown a simpler task next. This can be achieved with dynamic blocks.
Showing a Subset of All Trials
Studies frequently want to only show a subset of all trials to a single participant. For this, each block in the sequence has a numSamples variable. The following example will show each participant 2 of the 4 trials. numSamples works with all sequence orders, but is likely only useful in combination with random and latinSquare. If used with latinSquare, choosing a numSamples will ensure that each trial is seen the same amount.
sequence: {
order: 'fixed',
components: [
'introduction',
'consent',
{
order: 'latinSquare',
numSamples: 2,
components: [
'trial1',
'trial2',
'trial3',
'trial4'
]
},
'post-survey'
]
}
Attention Checks and Breaks
To add attention checks or breaks to your study, there is an interruptions object, which has its own components. The example below adds two attention checks randomly spaced out between trials 1-4. You are guaranteed that the first component will not be an attention check, and that you won't see two attention checks back to back.
sequence: {
order: 'fixed',
components: [
'introduction',
'consent',
{
order: 'latinSquare',
components: [
'trial1',
'trial2',
'trial3',
'trial4'
],
interruptions: [{
spacing: 'random',
numInterruptions: 2,
components: ['myAttentionCheckComponent']
}]
},
'post-survey'
]
}
You can also add interruptions deterministically at set intervals. The example below will put an attention check after the first and third trial.
sequence: {
order: 'fixed',
components: [
'introduction',
'consent',
{
order: 'latinSquare',
components: [
'trial1',
'trial2',
'trial3',
'trial4'
],
interruptions: [{
spacing: 2,
firstLocation: 1,
components: ['myAttentionCheckComponent']
}]
},
'post-survey'
]
}
Skip Logic
Some studies need more advanced sequencing logic, based on a participant's response to previous questions. For example, a participant should only be shown a second, simpler task if they got a first, difficult task wrong. This is possible to implement in reVISit sequences with the skip object.
The example below will jump straight to end if the consent form is answered with anything but yes to the field consentApproval, meaning the participant did not approve of the consent form. All skip conditions require labeling any components that you want to jump to with your own id, except for they keyword end, which always jumps to the default final component of the study.
sequence: {
order: 'fixed',
components: [
'introduction',
{
order: 'fixed',
components: ['consent'],
skip: [{
'name': 'consent',
'check': 'response',
'responseId': 'consentApproval',
'value': 'yes',
'to': 'end'
}]
}
'trial1',
'trial2',
'trial3',
'trial4',
'post-survey'
]
}
To check if multiple components are correct, for example that all attention checks were correct, you can do the following:
sequence: {
order: 'fixed',
components: [
'introduction',
'consent',
{
order: 'latinSquare',
components: [
'trial1',
'trial2',
'trial3',
'trial4'
],
interruptions: [{
spacing: 2,
firstLocation: 1,
components: ['myAttentionCheckComponent']
}],
skip: [{
'name': 'myAttentionCheckComponent',
'check': 'responses',
'to': 'end'
}]
},
'post-survey'
]
}
This example will go through every component named myAttentionCheckComponent, and if any response is incorrect, jump immediately to end.
You can also wait until multiple attention checks have been answered incorrectly to jump to end with the repeatedComponent check.
sequence: {
order: 'fixed',
components: [
'introduction',
'consent',
{
order: 'latinSquare',
components: [
'trial1',
'trial2',
'trial3',
'trial4'
],
interruptions: [{
spacing: 2,
firstLocation: 1,
components: ['myAttentionCheckComponent']
}],
skip: [{
'name': 'myAttentionCheckComponent',
'check': 'repeatedComponent',
'condition': 'numIncorrect',
'value': 2,
'to': 'end'
}]
},
'post-survey'
]
}
You can also use skip to jump around within your study. The example below skips the block hardQuestions if the participant gets both questions wrong in easyQuestions.
sequence: {
order: 'fixed'
components: [
'introduction',
'consent',
{
order: 'latinSquare',
components: [
'trial1',
'trial2',
],
id: 'easyQuestions',
skip: [{
check: 'block',
condition: 'numIncorrect',
value: 2,
to: 'moreEasyQuestions'
}]
},
{
order: 'latinSquare',
components: [
'trial3',
'trial4'
],
id: 'hardQuestions'
},
{
order: 'latinSquare',
components: [
'trial5',
'trial6',
],
id: 'moreEasyQuestions'
},
'post-survey'
]
}
After jumping to moreEasyQuestions, the sequence will continue as if you had gotten there naturally, so will continue on to post-survey afterwards.