- published: 22 Jan 2013
- views: 10500
In epidemiology and demography, age adjustment, also called age standardization, is a technique used to better allow populations to be compared when the age profiles of the populations are quite different.
For example, in 2004/5, two Australian health surveys investigated rates of long-term circulatory system health problems (e.g. heart disease) for the general Australian population, and specifically for the Indigenous Australian population. In each age category over age 24, Indigenous Australians had markedly higher rates of circulatory disease than for the general population: 5% vs 2% in age group 25–34, 12% vs 4% in age group 35–44, 22% vs 14% in age group 45–54, and 42% vs 33% in age group 55+.
However, overall, these surveys estimated that 12% of all Indigenous Australians had long-term circulatory problems compared to 18% of the overall Australian population.
To understand this apparent contradiction, note that the Indigenous population is comparatively young (median age 21 years, compared to 37 for non-Indigenous) due to relatively high birth and death rates. Because of this, Indigenous figures are dominated by the younger age groups, which have lower rates of circulatory disease; this masks the fact that their risk is still higher than for non-Indigenous peers of the same age.
Video is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.
Video technology was first developed for cathode ray tube (CRT) television systems, but several new technologies for video display devices have since been invented. Charles Ginsburg led an Ampex research team developing the first practical video tape recorder (VTR). In 1951 the first video tape recorder captured live images from television cameras by converting the camera's electrical impulses and saving the information onto magnetic video tape.
Video recorders sold for $50,000 in 1956, and videotape cost $300 per one-hour reel. However, prices steadily dropped over the years; in 1971, Sony began selling videocassette recorder (VCR) tapes to the public. After the invention of the DVD in 1997 and Blu-ray Disc in 2006, sales of videotape and tape equipment plummeted.
Later advances in computer technology allowed computers to capture, store, edit and transmit video clips.