I like really big population studies. The conclusions reached are valid and extremely accurate. Small studies with few participants are subject to many types of bias. The results of small studies are often debatable and not dependable.

The second Nurses’ Health Study enrolled 83,882 adult women 27-44 years of age. At the beginning of the study in 1991, all these women had normal blood pressure, (systolic 120 or less and diastolic 80 or less), and no diabetes, heart disease or cancer. These women were followed for 14 years through 2005. During the study, 12, 319 women developed high blood pressure and the rest didn’t.