To maximize the power to find disease association, we used a control population twice the size of the patient sample.
We chose to use a control population with solid organ malignancies; among these few had undergone chemotherapy, but on the contrary the neutropenic patients all received chemotherapy.
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.
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.
The cut-off value for IgG positivity was determined by using a negative control population of volunteers sampled in Marseille, France in 2008.
