Question

In Exercises 29–32, indicate whether the observational study used is cross-sectional, retrospective, or prospective.

Nurses’ Health Study II Phase II of the Nurses’ Health Study was started in 1989 with 116,000 female registered nurses. The study is ongoing.

Short answer

This is a prospective type of observational study.

Step-by-step solution

Given information

The observational study, which began in 1989 for phase II, comprises 116,000 registered female nurses.

The number of nurses is still being recorded.

Different forms of observational studies

A cross-sectional study is a study that is based on a single point in time. Values are recorded for a particular time.

A retrospective study is a study that is based on some point in time in the past. Values are recorded for a past period.

A prospective study is a study that is based on the current time-point and also continues in the future. Values are recorded over a long period.

Identification of the type of study

This study requires recording the number of registered nurses in the future as well. As the number of registered nurses is still being recorded, the observational study is prospective.