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.
Removing the tumor can improve neurological symptoms, provide tissue for diagnosis, help make other brain tumor treatments more effective, and, in many instances, improve the prognosis of a person with a brain tumor. A neurosurgeon is a doctor who specializes in surgery on the brain and spinal column. Surgery to the brain requires the removal of part of the skull, a procedure called a craniotomy. After the surgeon removes the tumor, the patient's own bone will be used to cover the opening in the skull. There have been rapid advances in surgery for brain tumors, including the use of cortical mapping.