Another key difference lies in the sampling error. With a cluster sample, the error can be higher compared to what can come from a random sample, as the variability within clusters may not be as representative of the population variability. However, this is often a trade-off for the logistic...
In epidemiology, cluster analysis has many uses, such as finding meaningful conglomerates of regions, communities, or neighbourhoods with similar epidemiological profiles when many variables are involved and natural groupings do not exist. In general, whenever one needs to classify large amounts of ...
The study population will be all individuals with CKD from general practices in eight localities across England. Randomisation will take place at the level of the general practices. The intended sample (three arms of 25 practices) powers the study to detect a 3 mmHg difference in systolic BP b...
We then used the Geographic Information System (GIS) [13] tool to assess the internal validity of our definition by mapping villages to the health centres in which their residents access healthcare. To reduce the risk of contamination between the two arms, a village is included in a ...
the lowest frequency in a given day of the tacs (≤ 8 per day) paroxysmal hemicrania hemicrania continua short-lasting unilateral neuralgiform headache with conjunctival injection and tearing (sunct) short-lasting unilateral neuralgiform headache with cranial autonomic symptoms (suna) epidemiology [...
The Malaysian cohort is a community cohort, while CLUSTer is an occupational cohort that is made up of a representative sample of public primary and secondary school teachers. The majority of studies in school have been on students rather than on the health and wellbeing of teachers. As ...
Exclusive breastfeeding will be based on 24-h maternal recall using the WHO definition of exclusive breastfeeding. We will also collect data on immunization, family planning/use of contraception, time spent in play, and episodes of diarrheal and acute respiratory tract infections among infants. We...
Resilience theory, which has arisen from the study of risk factors for, and their impact on, positive youth development represents one approach to improving adolescent mental or psychosocial well-being [12–18]. Whilst there is variation in the definition of resilience, it is generally agreed that...
Sample size The present study is likely to observe a significantly longer diabetes-free period in the intervention than in the control arm. Thus, the null hypothesis is that the diabetes-free period in the intervention arm is the same as that in the control arm. The sample size(S) needed ...
Epidemiology The prevalence of CH can be estimated at approximately 0,5 – 1.0/1,000 [3–12]. Table 3 summarizes the epidemiological studies on CH. Many of these studies are biased by the sample chosen and by the difficulties of diagnosing CH by mailed questionnaires or telephone interviews....