1-Why is it important to have a control group in a statistical study?

2- Give an example of a recent study that has been published in the last two months that used a control group. Describe that control group and the treatment group(s).

3-Give an example of a confounding variable in a study, and explain why it's confounding.

What is the difference between cluster sampling and stratified sampling?

Give an example of each.

4-Find an example of sampling bias in the media from the last two months. Share the source and describe the type of bias in your own words. Describe something that could have been done to improve on their method?