Different types of bias in research and discuss.

In last week we discussed research techniques, this week discussion focuses on the other aspects of research, please Discuss the following into detail with applicable in text citations and a minimum of three credible references per question.
1) Different types of bias in research and discuss.
2) Experimental and Non-Experimental Research
3) Distinguishing between a Sample and a Population and then compare at least two sampling methods (e.g. random sampling vs. stratified random sampling or convenience and quota sampling methods?
4) What specific steps would you have taken to obtain a representative sample?