By convention, specific symbols represent certain sample statistics. For example, 1  x refers to a sample mean. 2  s refers to the standard deviation of a sample. 3  s 2 refers to the variance of a sample. 4  p refers to the proportion of sample elements that have a particular attribute.or example, 1  P refers to a population proportion; and p, to a sample proportion. 2  X refers to a set of population elements; and x, to a set of sample elements. 3  N refers to population size; and n, to sample size.
The brain is one of the most important organs in the body and gives humans the capacity for language, art, and rational thought. A brain surgeon, or neurosurgeon, is a doctor that performs surgery on the nervous system, particularly the brain. He or she will also treat a wide range of problems affecting the central nervous system is the job of a brain surgeon.
Health Care Professionals. Neurology is the medical specialty which focuses on the diagnosis and treatment of diseases and disorders of the brain and nervous system. A physician who practices neurology is called a neurologist. A surgeon who operates on the brain is called a neurosurgeon, which is a surgical specialty rather than a medical specialty.