Question

Scientists did a 10-year study to investigate the effect of tagging penguins with either a metal strip or an electronic tag. In the student, a sample of 100 penguins were randomly assigned to one of two groups, then followed for 10 years. The study learned that, overall, penguins tagged using a metal strip had fewer chicks, had a lower survival rate (percent to survive over the decade), and on average took significantly longer on foraging trips than penguins who were tagged with an electronic tag.

1) What are the cases in this study? What are the variables? Identify each variable as categorical or quantitative.

2) Is this an experiment or an observational study? Why?

3) The description above indicates that the scientists found a strong association between the type of tag and various measures, with the metal tagged penguins having less success. Can we conclude that the metal tag is causing the problems?

Answer 1

1)

The cases(subjects) in the study are 100 penguins that were randomly assigned to two groups.

Variables:

Independent variables - Electronic tag and metal strip tag for penguins. These are categorical variables as they cannot be measured in numbers.

Dependent variables - Survival rates, number of chicks and foraging trip duration by penguins. These are quantitative variables as they have numerical value,i.e., they can be measured in numbers.

2)

It is an experiment because there is an intervention by the researchers in the form of tagging penguins with metal strip (treatment group) and electronic tag (control group).

3)

We can conclude that the metal tag is causing the problems because they assigned 100 penguins randomly to two groups and compared treatment group(metal tag) with control group(electronic tag) by following for 10 years which would significantly reduce external bias, if any and no potential confounders seem to effect the result, if any.

The main reasons for the strength of the conclusion are:

a) Large sample (100).

b) Random assignment.

c) Control group (electronic tag).

d) Following for considerable amount of time (10 years).