Exercise 3: Gestational Age and Birth Weight

An investigator wishes to study the relationship between gestational age and birth weight to estimate a newborn's birth weight based on knowledge of their gestational age.

She identifies 1000 newborns whose gestational age could be accurately dated in days. From among these she selects 150 premature newborns with gestational ages between ages 30 and 2 weeks and 150 full term newborns with gestational ages between 38 and 40 weeks. She then obtains newborn's birth weight in grams.

She asks two basic questions of statistics even before collecting the data.

1. Estimation: What measurements should be used to summarize the data which will be found in this investigation?

2. Inference: How will we use the study data to investigate whether there is a real relationship between gestational age and birth weight for newborns in the population from which the investigation's sample was selected?