Statistical Design (take notes)

• Surveys are sets of questions given to people to seek their responses.

• Experimental studies collect data by directly influencing something to determine how another thing is changed.

• Observational studies collect data without influencing things directly.

What is the difference between an observational study and an experimental study?

• In an observational study, you collect the data without influencing things directly to answer your question. In an experimental study, you directly influence things and collect data to answer your question.

Possible answer

No. Sample reasoning: Since the data was collected through a survey, only an association can be determined and not a causal relationship. It’s possible that some people may have lower energy in the evening for other reasons and they watch a lot of television since they do not have energy for other activities.

Possible response

The design is bad. The experiment does not address the original question. It might test how the sweeteners affect the flies’ ability to fly, but not their preference.

Possible response

The design is good. The flies should be attracted to the sweetener they like and drink more often from that bowl.

A researcher discovers that the diameter of a person’s pupil in their eye is directly related to how beautiful they find the image they are looking at. The researcher wants to know whether reading an article about climate change influences people’s perception of pictures of a city in terms of beauty. 100 people have volunteered to be a part of the study.

​

​

​The volunteers are split into 2 groups by a random process. One group will read the article and the other will not. Everyone will then look at the city pictures and the diameter of their pupil will be measured while they look at the pictures.

A researcher discovers that the diameter of a person’s pupil in their eye is directly related to how beautiful they find the image they are looking at. The researcher wants to know whether reading an article about climate change influences people’s perception of pictures of a city in terms of beauty. 100 people have volunteered to be a part of the study.

​

​

​The volunteers are split into 2 groups by a random process. One group will read the article and the other will not. Everyone will then look at the city pictures and the diameter of their pupil will be measured while they look at the pictures.

​

​What does a random process mean exactly?