Dear Imelda, I think it depends upon the level of your dissertation, the depth and extent of the data you have collected and whether your qualitative analysis has reached a saturation in the theory you have generated

From my experience, undergraduate and masters dissertations often have this size of sample but you might need more for an MPhil or a PhD.

I'm also a little concerned about your apparent convenience sampling which could lead to bias in your analysis.

It depends on the overall design of your research and your research question. For a robust quantitative analysis involving many predictors you would probably need much more participants, say a minimum of 3 to 5 participants per cell created by crossing the selection criteria (e.g. age, education, gender, etc.). For a more qualitatively oriented study 6 could do just fine. Like I said, it all depends on the type of issue you wish to explore and the methods you wish to implement.

Dear Imelda,

Since you are doing a qualitative study, 6 participants would be enough, provided:

a. These 6 participants are providing you with all the data that you would need for your study.

b. Your study has enough rigor and trustworthiness.

c. Sine you as a researcher are the research instrument, you need to have indepth knowledge of the subject you are researching.

I would advice you to read Stake, Yin, Charmaz thoroughly and create a strong research protocol before venturing out for data collection.

Happy Researching!

Dear Imelda,

I think for the case study method, 6 participants is sufficient, which is important meet your criteria and there are variations between them. 

Success for you! 

I think this urls will help you out. 

http://www.qualitative-research.net/index.php/fqs/article/view/1428/3027

http://eprints.ncrm.ac.uk/2273/4/how_many_interviews.pdf

Best of luck!!

Thank you for all the comments and encouragements. God bless you all ^_^