To maximize the power to find disease association, we used a control population twice the size of the patient sample.
This highlights the importance of using a control population as when compared with our general pregnant population PET rates differ between T2DM and controls.
The threshold to determine debris and GFP– versus GFP+ embryos was set using a control population of untreated wild-type worms.
hESC-derived hNSCs (Liu et al., 2012) were used as a control population.
It was also specific to Ilp7 neurons, given that GCaMP3 fluorescence intensity was unaffected by yeast in the Capa-expressing Va neurons, used as a control population of six unrelated peptidergic efferent neurons (Suska et al., 2011).
In a comparison of two golf-oriented retirement communities in middle Tennessee, one abutting a wildlife-management area and one 20 miles away from the area used as a control population, Standaert et al. found seroprevalence rates of 12.5% and 3.3%, respectively (12 ).
Projects such as the 1000 Genomes Project (1000 Genomes Project Consortium, 2012) or the NHLBI Exome Sequencing Project (www.evs.gs.washington.edu/EVS/) included large cohorts from various ethnicities, and have been frequently used as a control population for filtering out potential benign variants observed in a disease cohort.
First of all, most studies did not use a control group with the same population characteristics as the treatment group.
Comparison of health outcomes during the intervention to both before and after the intervention in the population of interest, as well as use of a control population to assess whether any temporal changes in the population of interest were also seen in populations not impacted by air quality improvements, should aid in minimizing residual confounding by these long term time trends.
Use of a control population of a different age group (but the same state) from that of the cases, however, limited the ability to adjust for secular changes; also, our inclusion of a heterogeneous group of surgeries had uncertain implications for clinical value and cost effectiveness.
