First, an estimation of mortality rates for singleton live births in each of the measured age ranges was conducted according to the year of survey, using a method similar to that described by Rutstein and Rojas.
Although menarche timing was assigned by retrospective self-reported data, the observed mean age at menarche in our study of 12.96 years+/−1.41 years (median = 13 years; n = 1140) matched longitudinally measured age of menarche in Western societies ranging from 12.6 to 13.4 years rather well [17] [20].
Survey items measured gender, age range (categorised in increments of ten years6, residential postcode, manageability on household income, highest level of education, private health insurance coverage, health care card status, employment status, and marital status.
Body Si content for the tissues analysed is shown in Fig. 5 and Supplemental Table 3. Bone and skin accounted for 75 87% of the Si content measured, across the age range and, collectively, connective tissues accounted for 80 89% of the measured Si content.
Related to this, we included parent-proxy report of patients up to 22 years old, which is outside the measure validation age range, because their underlying disease causes limitations that differentiate young adults with chronic respiratory insufficiency from their typically developing peers.
The broad age range measured here is unlikely to indicate an occupation period of 1000 years.
We did not create age adjusted standard deviation scores, as the childhood outcomes were measured in a small age range without changes in standard deviation.
The evidence from these studies shows that income measures in the age range between the early-30s and the mid-40s should be least affected by life-cycle bias when dependent variables are proxied.
We were also unable to conduct cross-lag analyses due to inconsistent alcohol measures across the age range of interest.
