Three group of researchers would like to seek your help to determine the methods of data collection and methods of sampling for the following statistical analysis. Propose the suitable method of data collection and method of sampling for each of the following with sufficient justification why you recommend your selection, over other possible methods.

a. Analyze the voting intention of Australian voters for upcoming election.

b. Investigation of reasons for not Big 4 banks (NAB, ANZ, CBA and WBC) passing on the full interest cuts introduced by reserve bank of Australia to its borrowers.

c. Understand the demographic profile of the community living in Hume city council, Melbourne

d. Examine opinions from adults on legalizing marijuana use in Australia.

e. Estimation of the average age of children in city of Melbourne.

There are a variety of approaches to data collection and sampling, depending on the category of interest. Here, it is to identify which data collection and sampling methods can be used to conduct the following research.

a. Analyze the voting intention of Australian voters for the upcoming election: Here, for data collection, the questionnaire method can be used because it involves a large number of people. It means that there are few final answers to large sample size.

To do this research, the method of random sampling can be applied. It is because no one travels the whole of Australia questioning every single citizen about their choice. It is to question and draw conclusions from any random citizen of Australia.

b. Investigation of reasons for not Big 4 banks (NAB, ANZ, CBA, and WBC) passing on the full interest cuts introduced by the reserve bank of Australia to its borrowers: Here, the interview method can be used in which one can interview any financial or banking expert to know the possible reasons. This research is carried out by using a convenience sampling method. For this purpose, the person will approach any expert in this field so that it is easy to approach and can interview in accordance with the bank's point of view.

c. Understand the demographic profile of the community living in Hume city council, Melbourne: To understand this, a survey can be conducted at the location where the required details are sought from the people living there. To carry out this research, a stratified sampling method can be used. It includes grouping people with similar characteristics into subgroups, which makes it easier to understand their demographic profile.

d. Examine opinions from adults on legalizing marijuana use in Australia: To understand this, the method of the focus group can be implemented on adult options about legalizing the use of marijuana in Australia. Since, this method involves interviewing, surveying, and monitoring a focus group, here, senior groups can be interviewed, surveyed, and monitored.

e. Estimation of the average age of children in the city of Melbourne: For the estimation of the average age of children, the documentation and records can be used. As it contains census reports or similar material, it is possible to estimate the average age of children there. The method of stratified sampling can be used because it involves separating the children's data from the overall data.