"Exercise Beats Calcium at Boosting Girl's Bones" reports on a study published in the Journal of Pediatrics in 2004 that found that "girls with better muscle development also had stronger bones." Muscle development was measured in terms of the girls' lean body mass, and the study's author explained: "A 1 kilogram increase in lean mass was associated with a increase in their bone strength."21
a. Can we assume this was an experiment or an observational study?
b. Did the individuals studied constitute a sample or an entire population?
c. Did the study find a positive or a negative correlation?
d. Is the number referring to the correlation r, the intercept b0, or the slope b1?
e. Is the number a statistic or a parameter?
f. If researchers want to conclude that there is a relationship between muscle development and bone strength for all girls, are they mainly concerned with data production, displaying and summarizing data, probability, or statistical inference?