However, concerns about database studies include data validity, lack of detailed clinical information, and a limited ability to control confounding.
Following a trail of human animal encounters from the seventeenth-century Chesapeake to the Civil War era southern plains, Smalley shows how wild beasts and their human pursuers repeatedly transgressed the lines lawmakers drew to demarcate colonial sovereignty and control, confounding attempts to enclose both people and animals inside a legal frame.
Four of the six studies [ 52, 54- 56] did not report attempts to control confounding.
These early studies all had < 150 subjects and did not adequately control confounding.
In general terms, a misclassified confounding variable hinders the ability to control confounding.
Purposeful selection, as proposed by Hosmer and Lemeshow (2000), was used to select variables to control confounding in multivariable models.
8 9 Studies at a population level are none the less limited by their inability to control confounding.
The longitudinal study evaluated a sample of teachers before and after training with participants acting as their own controls, which made it possible to control confounding individual characteristics.
bAll analyses include baseline age, prior history of study disease, systolic and diastolic blood pressure, smoking history, treated diabetes history, prior HT use, and body mass index as regression variables to control confounding.
One theoretical advantage of using in vitro models to study disc degeneration is the ability to carefully control confounding environmental variables, which may differ between individual animals such as nutrition and the loading environment.
aAll analyses also include baseline age, prior history of study disease, systolic and diastolic blood pressure, smoking history, treated diabetes history, prior HT use, and body mass index as regression variables to control confounding.
