View Full Version : Issues with an Internet based study

05-19-2004, 09:00 PM
Hey all!

I have this big dilemma that I thought that someone here could help me solve. I've got this project, that would require me to make a study, where people would have to fill out an electronic questionnaire on the Internet. But making an Internet-based study scientific, there are some problems that need to be solved.

First of all, if a questionnaire is available for anyone to answer on the web, there is a chance that somebody might manipulate the results of the study by entering more than once and/or giving out false information. This may be the case, where eg. companies or anyone else would want the study to give a certain result.

So, to avoid this, I would need to make a questionnaire wherethe user can fill out only once, and where several people can fill out the form from the same computer. As this study is aimed at 12-18 year olds, it's quite certain that quite many of them will access the questionnaire from computers at school.

I've been thinking how to solve this, but I just can't think about a good solution. One way of doing it would be to make the questionnaire only accept one submission per IP-address, but this would exclude anyone else trying to fill out the questionnaire from that computer.

Another way would be to ask the user for his/her e-mail address, so that at unique password would be sent to him/her to able to log on to the questionnaire. By doing this however, you first of all exclude everyone without an e-mail address, and also those who think it's too much trouble to fetch the password (especially if they have a web based e-mail account) or those who don't want to give out their e-mail address.

So you see, I'm in a quite big dilemma here. I know that some of you might wonder why I just don't do this the old-fashioned way - in paper form - but the reason why is simple: I won't have time to collect and analyze the results manually.

I've posted here before asking if anyone knows how to make a good questionnaire (http://www.codingforums.com/showthread.php?t=37601), so if anyone still could help me, I'd really appreciate it.


05-19-2004, 09:40 PM
Depending on how long the questionnaire is, I doubt many companies would hire some to just sit there and fill out your questionnaire (although it's possible I guess...). I would think that they would create a bot of some sort..

I've seen some sites that put an image with random alphanumeric characters and ask you to input what you see. As long as those match then you can proceed. Perhaps you can incorporate something like that into your 'authentication'?

Also, depending on the topic of your survey, people without email are pretty much useless. I wouldn't care about their input on my survey :D

You might be able to limit them using cookies (however people could just turn their cookies off..). In your example regarding users at schools, most school computers require a username/password to get in (so that the general public doesn't come on and mess around with the computers..), so that way each user will have a cookie.

For the most part you won't be able to COMPLETELY prevent the same user from submitting your questionnaire a bunch of times. You might be able to deter this from happening a little bit, but without a login password or something you won't have anything full-proof.

I guess the other aspect is how you market your questionnaire...

I don't know too much about this kind of stuff, and I don't have the most experience with this sort of stuff. Hopefully someone else on the board will be able to lend you some better advice/tactics.

Good luck,

05-19-2004, 10:14 PM
i would recommend the email variation. send them a code, and have them "verify" themselves. there is no sure-fire way of preventing people from questionairing more than once. even in real life, identities can be swapped. the internet opens up a whole new playing field, with email addresses galore, anonymous proxy servers, and large corporate networks to hind behind.

ip blocking is definitly not recommend.

cookies would be a pretty good deterrant, unless 2+ 12-18 year olds use the same computer, which would be pretty frequent, i think.

email sounds liek the best idea to me!

05-19-2004, 10:47 PM
You could do a timeout script with IP adress. Unless they were are using a dial up connection, this should work. Most schools, dont use dial up connections, so this would be good.

You could create some sort of log script that saves the IP adress, and the last time that IP adress clicked send. You could then have some sort of PHP script in the page where they send you the questionnare, read the log script, check their IP adress, and add 20 minutes to the time saved. If they try and click send between the time they first clicked submit and the 20 minutes (say, 5 minutes after clicking send the first time) it could redirect them to some page telling them they must wait 20 minutes to resubmit the form. This would somewhat disgourage people from submitting multiple times, and us kids would probably get sidetracked between that 20 mins and go find something else to do other than ruin your study :rolleyes:

BTW, I dont know what schools will be viewing this site, but all of my schools that I have ever gone to never let us touch computers unless its school related or were doing something for teachers, and I move around quite often. ;)

05-21-2004, 12:24 PM
Thanks guys for all your replies! I myself would go for e-mail validation, but submitting your address (if the user even has one), might be too big of an obstacle for taking part in the study. But then again, that might be the only way of (almost) eliminating manipulation...

l3vi's suggestion also seems like a good solution, but as some as the entrants might be filling out the questionnaire from home (where some ppl actually have dial-up connections), this might not work.

Are there any other solutions to this problem? If anyone knows how to help me, pleas do! Otherwise, thanks to those who've contributed with their help!