Missing data are a major concern for surveys: unless the absence of the variables in question is completely random, the analysis is likely to be biased [ 21].
Low response and reporting errors are major concerns for survey epidemiologists.
Obesity, they found, ranked behind AIDS, cancer, heart disease and diabetes as a "very serious concern" for those surveyed, even though obesity kills more people than AIDS and often underlies heart disease and diabetes.
The insignificant parameters of 1/Birds and 1/Reptile variables indicate that an increase in the species of birds and reptiles is not a major concern for the surveyed residents.
The impact of proxy response bias on the validity of the estimates is a significant concern for researchers when surveys are conducted among the elderly or disabled.
The use of other forms of data collection such as computer-assisted self-interviewing (CASI) and the internet have shown promise in collecting sensitive information [ 43, 45, 46] although determination of epidemiological based sampling frames is still of concern for web-based surveys.
Topping the list of concerns for those surveyed were re-establishing a social life (41%), feeling lonely and missing friends and family (34%), especially among women.
One of the greatest issues for concern in the survey for large enterprises is the risk of disruption from new entrants.
