Costs of physical inactivity in Canada
The CBC report glosses over the methods. Normal I guess. The paper uses a three (though I think its really four) step approach to estimating the costs of physical inactivity. First, a meta analysis was conducted to estimate the risk of the top 7 physical activity related chronic diseases. Second, he calculated the population attributable risk (PAR) of physical activity for each chronic disease. Third, he applied the PAR to the total cost estimate of each chronic disease using data from 2000. The finally adjusted the cost estimates for inflation and population size changes up to 2009.
As Ian notes in the limitations:
However, using the prevalence-based approach produces cost estimates that are more theoretical (e.g., rely on several assumptions) than concrete.
I know this was a short report but I agree that there are lots of assumptions particularly around temporal stability of each estimate and the potential impact of multiplying estimates from various years. I wonder if a potential solution would be to standardize (e.g., inflation and population size) all of the estimates to a particular year, say 2000, then project into the future. I guess that does not help the problem all that much.
Anyway, interesting paper. Have a read.