I think that communicating the overall purpose of your research may be too much.  Explain to them the purpose of the specific survey, such as "to understand your reactions to ______ that we did in class."

Very true Michael. Communicating in way to get unbiased response is a skillful art. I guess, it is  possible only with the experience. 

Can you suggest some references to the literature?

Thank you

Saidatt

I think communicating the purpose of the research (in a concise and clear way), improves the availability of the questionnaire recipients to participate in the research. However, I agree that communicating in a way that creates unbiased responses is very complicated and sometimes quite slippery. Are you sending the questionnaire through email/post or are you getting personally in touch with the questionnaire recipients? If you're sending it through email you can better control your communication in order to avoid (at least try to avoid) unbiased responses, therefore I think it could be useful to communicate the overall purpose in order to focus the attention of the recipient and avoid misunderstanding on the type of research you are carrying out. If you are directly  speaking to the questionnaire recipient I guess it would be better to explain the purpose of the specific survey and then summarize the purpose of the overall research in a few, very clear, points. Good luck with your survey!

Thank you Elena for the good wishes and the suggestions!

I believe it might be thought that questionnaires applied are actually made for different research models. We can not think or waiting for something perfect, but by questionnaires and theories that are in fact further consonants with our research and others do not. Good luck

Thank you Rafael.

I meant psychometric instruments for gauging the attitudes 

While communicating the purpose, the researchers' objective is to elicit maximum response with accuracy and validity.

Looking forward to more tips and suggestions in this regard.   

Your IRB may require that in the process of gaining informed consent, you will need to explain certain things about the nature and purpose of the study and the informants' cost or gain. Check with your IRB.

Thanks Bill for the information. If possible, Can you please share the IRB guidelines?

Explaining the purpose of the research helps to recruit participants through their interest in a subject which quite often allows subsequent snowballing recruitment.  It also supports thoughtful responses because they feel they belong to something rather than adjunct to it.  To address issues of bias, having space for comment under each question lets participants clarify their responses if the options available to them would otherwise not adequately reflect the answers they would like to give.

  A general answer to this question may be misleading. I can attempt to advise you if I know the purpose of the survey, the target population as well as some of the major topics which will be covered in the survey.

Usually yes. You tell the respondents the reason for the research, especially where the their identities are not required. The main aim of the research is to add or advance knowledge. But where the reason for the research may scuttle this advancement and the respondents become wary, hostile or may not even wish to volunteer information, you do not need to tell them anything. You just cover it with a bland language.

I think it is ethical to communicate the purpose of a research in a questionnaire survey. I consider it very critical to do this especially in the introduction paragraph of the survey questionnaire. Below is a sample introduction to the survey questionnaire which I did.

 Introduction: This survey is planned to help improve on the management of the environment in Uganda. The purpose of the study is to find out the success of the environment management policy awareness communication campaigns in your area. That is why it is important to hear from you. Spare just 5 minutes or so to respond to the questions in this form. The results are for academic purposes, but they may be published, and the policy makers may use them. This enumerator is fully identified. We sincerely appreciate and value your time. Thank you for your cooperation. [Researcher’s telephone:]

This disclosure also improves the researcher’s integrity and communication with the prospective respondents. As a result, data quality or publications quality are improved or enhanced.

Thank you Wilson for sharing a specimen of a survey research purpose. It seems to be interesting. 

Minimizing the response bias should be on the top of the agenda while communicating the  research purpose. Its not easy doing especially in behavioral research. 

Looking forward to some more sample specimen of different kinds for different fields of research.  

In my opinion it is good to state the purpose of research to participants. If I am a participant (and of course I participated a number of surveys) I am eager to know in what context I have been selected for the survey. My answers will be spontaneous but ambiguity will not be there whether I am worth for this survey. This will give participant a confidence about the future use of the data as well. All the best. 

I agree with Mr Jayan,s view that statement of the purpose helps the respondent to restrict his/her responses within the context.