An investigator wishes to estimate systolic blood pressure (SBP) in adults based on knowledge of body-weight index (weight in kilograms divided by the square of the height in meters), salt intake (mg of NaCl per day), and gender.

To investigate the relationship between these characteristics and SBP, the investigator obtains a random sample of 1,000 adults.

Even before collecting the data the investigator asks:

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

2. Inference: How do we use the study data to investigate whether there is a real relationship between the body-weight index, salt intake, and/or gender and SBP in the population from which the investigation's sample was selected?