Worksheet: Observational Studies

In this worksheet, we will practice how to identify an observational study and differentiate between its variables.

Q1:

A large garden furniture seller wants to compare the resistance of two of their product lines in real use conditions. They decide to produce a random sample from their client database and ask them about the conditions of their garden furniture while recording the time of their purchase. Which of the following is probably NOT a confounding variable?

  • Ahow clients store their garden furniture in winter
  • Bclimate in which the furniture is kept
  • Cmonth in which the furniture was purchased
  • Dage of the people in the household
  • Enumber of people in the household

Q2:

A negative correlation has been observed between the number of pirates in the world and the global average earth temperature; that is, the fewer pirates there are, the colder the earth's temperature.

Do you believe one can conclude that the decline in the number of pirates causes global warming?

  • Ayes
  • Bno

Which of the following could be the lurking variable here?

  • Adeforestation
  • Bclimate
  • Cregion of the world
  • Dtime
  • Eglacier melt

Q3:

A positive correlation has been observed between the amount of sun cream sold and the occurrence of skin cancer.

Do you believe one can conclude that sun cream causes skin cancer?

  • Ano
  • Byes

Which of the following could be the lurking variable here?

  • Asun cream composition
  • Bsun exposure
  • Cpollution
  • Dozone depletion
  • Etime of the year

Q4:

A recent article in the BBC Health News section describes a study concerning dementia. According to the article, researchers followed more than 11,000 people with dementia over a period of 12–14 years. They found that smoking, diabetes, and high blood pressure were all factors in the onset of dementia. What type of study is this?

  • AThis is an observational case-control study.
  • BThis is an experimental cohort study.
  • CThis is an observational cohort study.
  • DThis is an observational cross-sectional study.
  • EThis is an experimental case-control study.

Q5:

In 1993, the National Institute of Environmental Health Sciences funded a study in Iowa regarding the possible relationship between radon levels and the incidence of cancer.

The study gathered information from 413 participants who had developed lung cancer and compared those results with 614 participants who did not have lung cancer.

What type of study is this?

  • AThis is an experimental case-control study.
  • BThis is an observational cross-sectional study.
  • CThis is an observational case-control study.
  • DThis is an observational cohort study.
  • EThis is an experimental cohort study.

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