Stratified sampling is not multistage. Cluster sampling is a good introduction can be found in:

https://www.amazon.com/Elementary-Survey-Sampling-Richard-Scheaffer/dp/0840053614/ref=sr_1_1?keywords=Elementary+Survey+sampling&qid=1564737218&s=gateway&sr=8-1

or

https://www.amazon.com/Sampling-Techniques-3Rd-William-Cochran/dp/8126515244/ref=sr_1_1?keywords=sampling+techniques&qid=1564737326&s=gateway&sr=8-1

Best wishes, David Booth

Dear Prof. David Eugene Booth Thank you very much for your answer and the links. Please could give any advise on how to best analyse the collected data?

I will soon buy the books.

Thank you, Sir

Dear Difo Voukang Harouna,

I would recommend you a regression analysis with a multifactorial hierarchichal (nested) experimental design. It works well in R with the package (nlme) or (lme4) depending on the distribution of your data.

I would also recommend you the following introduction

http://www3.imperial.ac.uk/pls/portallive/docs/1/1171923.PDF

Kind Regards,

Lana Dobrindt

Hi. There are several things., The big one is I don't know your research question(s). I do agree with Dr. Dobrindt that regression is probably a good thing to think about.The sampling books both have a chapter on the intersection with regression . In addition to her suggestion you might look at this link which is about Gelman's work in this area and has pdf's of some of his papers which might be helpful:

https://www.google.com/search?q=gelman+multilevel+regression+and+poststratification&rlz=1C1CHBF_enUS847US847&oq=Gelman+regression+and&aqs=chrome.2.0j69i57j0.27004j0j8&sourceid=chrome&ie=UTF-8

I had the pleasure of talking to Andrew once and he's a very helpful guy. Wish you the best, David Booth

Dear Dr. Lana Dobrindt thank you very much for this wonderful suggestion, I will try it right away and come back to you if I encounter any challenge, please.

Thank you

Dear Prof David Eugene Booth Thank you very much for the useful and ressourful links. I am still studying the suggested possibilities.

Thank you

Dear Dr. Difo Voukang Harouna ,

You are very welcome and you can contact me anytime if you need some more help.

Kind Regards,

Lana