In a study to determine the incidence of a chronic disease, 150 people were examined at the end of a 3-year period. twelve cases were found, giving an incidence rate of 8%. fifty other members of the initial cohort could not be examined; 20 of these 50 members could not be examined because they died. does this loss of subjects to follow-up represent a source of bias that may have affected the study results? answer yes or no and provide an explanation.

voluntary muscles are controlled by the cerebellum.

estuaries are the partially enclosed coastal bodies of brackish water formed at the mouth of sea where river meets an ocean. it is a transition zone between river and sea water so estuaries are influenced to both marine environment such as tides, waves and to riverine such as flow of fresh water and sediments. the mixing of sea and fresh water provide high level of nutrients, making estuaries a high product habitats.

many estuaries suffers degradation from a variety of human activities like erosion from deforestation, overgrazing, overfishing, drainage and eutrophication.

so from the above statement answers will be

1. false as estuaries are formed due to both brackish and freshwater.

2.true, due to high productivity estuaries are breeding ground for many marine species.

3. direct and indirect activities of man that contribute to pollution and deposition of sediments.