Allow only specified workers to complete your Mturk HITs

The other day I posted some code that allows mturk requesters to exclude workers based on a black list (here). This is typically used when someone already completed your survey, but for one reason or another you can’t just extend your already created HIT. The code in there actually started as the inverse. Instead of wanting to block certain people, a colleague wanted to only include certain people. Rather than dealing with the under-powered qualification system (under-powered for mturk web interface users at least), I figured it would be easy to just create a white list of worker Ids, and exclude everyone else from HIT. This way seemed faster than somehow creating a qualification test, or other method of excluding/including workers.

Again, this is very flexible and easily changeable. I, for instance, don’t rely on client-side programs (i.e. JavaScript) for validating users. Instead of checking the ID against a list declared in JavaScript, I send the data to server-side PHP script which returns the validation term, and if validated the URL to send workers to. The changes that would need to be done for this is to remove the url variable initialization, and add an AJAX request instead of the check() function call for when the HIT is accepted.

This code below is copy-and-pastable. Just change the Title, Instructions, target URL (where to send workers who are allowed), and create a white list of worker IDs. See the post linked at the top for how, but you will need to wrap all ids in quotation marks, and separate them by a comma. Last, change the conditional instructions to tell the worker what to do when they are on/off the list, etc.

Here’s the code (also here):

1:  <h1>TITLE - change this</h1>  
2:  <p>INSTRUCTIONS - change this</p>  
3:  <div id="idcheck">&nbsp;</div>  
4:  <p><textarea cols="80" name="comment" rows="3"></textarea></p>  
5:  <script type='text/javascript'>  
6:  var url="URL GOES HERE";//The URL that the user will go to after they are checked (i.e. the survey url). Change this.  
7:  var workers=new Array("test1","test1","test3");//This is your white list. Change this. All IDs must be enclosed in quoation marks (single or double), and separated by a comma  
8:  //Below is a utility function that checks if a given value is in an array. This will be used to check if the id (given value) is in the black list (an array)  
9:  Array.prototype.contains = function(k) {  
10:    for(var p in this)  
11:      if(this[p] === k)  
12:        return true;  
13:    return false;  
14:  }  
15:  //HTML instructions and form for ID input  
16:  var naCheck="<p>To see if you are qualified for this survey, enter worker ID below and click \'Check ID\'</p><p><textarea rows='1' cols='20' id='idinput'></textarea></p><div id='ok' onclick='check(false)' style='border: 3px solid black;cursor: hand; cursor: pointer; background-color:gray;color:white;width:70px;height:20px;text-align:center;margin-left:10px;'>Check ID</div>";  
17:  var href=window.location.href.toString();//Get URL of mturk webpage which may or may not include the worker ID  
18:  var queryString={};//storage variable for query string variables  
19:  href.replace(new RegExp("([^?=&]+)(=([^&]*))?", "g"),function($0, $1, $2, $3){queryString[$1] = $3;});//Populates variable named queryString (created above) with the actual queryString variable names and values  
20:  //If queryString contains a variable names workerId, check if the black list contains that value of that variable, if not, ask the user to input their ID.  
21:  if(queryString['workerId']!=undefined)  
22:  {  
23:       check(queryString['workerId']);//Check ID against white list  
24:  }  
25:  else  
26:  {  
27:       document.getElementById('idcheck').innerHTML=naCheck;//Add HTML necessary to ask for id input  
28:  }  
29:  //This function will check the ID given against the white list, or if not given will check the ID input into the text box against the white list  
30:  function check(id){  
31:       if(id==false){  
32:            if(workers.contains(document.getElementById('idinput').value))  
33:            {  
34:                 //Input ID found on list -- ask to accept, when this happens the page reloads and the program starts over
35:                 document.getElementById("idcheck").innerHTML="Your ID is on the list of qualified workers. Please accept the HIT to continue.";  
36:            }  
37:            else  
38:            {  
39:                 //Input ID not found on list -- ask not to accept
40:                 document.getElementById("idcheck").innerHTML="Your ID is not on the list of qualified workers. Please do not accept the HIT.";  
41:            }  
42:       }  
43:       else  
44:       {  
45:            if(workers.contains(id))  
46:            {  
47:                 //Actual ID found on list -- send to survey
                   document.getElementById("idcheck").innerHTML="<p>To proceed to the survey <a href='"+url+'&workerId='+id+"' target='mturksurvey'>click here</a>";
49:            }  
50:            else  
51:            {  
52:                 //Actual ID not found on list -- Ask to return HIT
53:                document.getElementById("idcheck").innerHTML="Your ID is not on the list of qualified workers. Please return the HIT. If you previously entered your ID and were told to accept the HIT, you likely did not enter the correct worker ID.";   
54:            }  
55:       }  
56:  }  
57:  </script>  

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5 thoughts on “Allow only specified workers to complete your Mturk HITs

  1. Pingback: Changing Mturk submit button functionality & A new to prevent duplicate workers on separate HITs | the:behavioral:lab

  2. Dinis on said:

    If I understood it well this will still allow workers to accept the HIT. Is there any way to prevent them from accepting the HIT unless they are on the list? I am fairly new to this so sorry if I am wrong. Thanks.

    • Using Javascript or anything else from within the HIT, no. There may be some ridiculously complicated thing you can do, but I can’t think of it right now and it would be so unweildly I would just find another way. That other way would be to use Mturks qualification system. You would give your workers a custom qualification, and then only they can see and accept your HIT.

      • Dinis on said:

        Thanks doe your reply! I figured it out in the mean time and used the qualification system as you suggest.

  3. Dinis on said:


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