In Data 1.3 on page 10, we describe a 10-year study in which scientists investigated the effect of tagging penguins with either a metal strip or an electronic tag. In the study, a sample of 100 penguins were randomly assigned to one of the two groups and then followed for 10 years. The study found that, overall, penguins banded 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.

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

(b) 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?

(c) To investigate a relationship between each of the following two variables, what graph or table might we use? What statistics might we compare or use?

i. Type of tag and number of chicks

ii. Type of tag and survival

iii. Type of tag and foraging time

iv. Foraging time and number of chicks v.

v. Foraging time and survival

Foraging time and survival

Data 1.3 on page 10

Do metal tags on penguins harm them? Scientists trying to tell penguins apart have several ways to tag the birds. One method involves wrapping metal strips with ID numbers around the penguin’s flipper, while another involves electronic tags. Neither tag seems to physically harm the penguins. However, since tagged penguins are used to study all penguins, scientists wanted to determine whether the metal tags have any significant effect on the penguins. Data were collected over a 10-year time span from a sample of 100 penguins that were randomly given either metal or electronic tags. This included information on number of chicks, survival over the decade, and length of time on foraging trips.