We need to learn how to work with massive incomplete and biased data: social media is not a statistically representative sample of a population; the demographics of users are frequently unknown; not all posts are geo-referenced when they are published.
A reduction of 120 g in birth weight was reported (using documented birth weight only) from Zimbabwe (in a nationally representative sample from a demographic health survey of 1999), where only the main type of fuel was ascertained, although multiple fuel use was also reported to be common practice (Mishra et al. 2004).
However, no single school can provide a representative sample of the demographic details of all schools.
They are, as I suspected, a mixed bunch, and I believe a reasonable sampling of this demographic A "mixed bunch" indeed.
If the pH and DP data for a representative sample of a large collection is known, demographic curves can be plotted, looking at progressive loss of fitness for use of collection items.
In the GEMS, matching controls (for sex, age, and community) were sampled from a demographic surveillance database of the area and included if they reported no diarrhea within the previous 7 days.
La Cañada High School juniors have been selected as a "scientific sample," whose answers will be comprehensively reviewed by SBAC as part of a representational sample of California's demographic.
We examine the association between private sector participation and self-reported measures of utilization and equity in deliveries and treatment of childhood respiratory disease using regression analysis, across a sample of nationally-representative Demographic and Health Surveys from 34 SSA economies.
In the remaining cases, no genetic sample of the demographic grandmother was available.
The sample was selected with the assistance of a demographic consulting company applying a face to face interview (N = 2509; mean age = 49.4, SD = 18.2; 55.8% women).
