what are the common measures of central tendency
Central tendency The most common measures of central tendency are the arithmetic mean, the median and the mode. A central tendency can be calculated for either a finite set of values or for a theoretical distribution, such as the normal distribution. Occasionally authors use central tendency to denote "the tendency of quantitative data to cluster around some central value."[2][3]
Central canal Throughout the cervical and thoracic regions the central canal is situated in the anterior third of the spinal cord; in the lumbar enlargement it is near the middle, and in the conus medullaris it approaches the posterior surface. It is filled with cerebrospinal fluid, and lined by ciliated, columnar epithelium, outside of which is an encircling band of gelatinous substance, the substantia gelatinosa centralis (or central gelatinous substance of spinal cord). This gelatinous substance consists mainly of neuroglia, but contains a few nerve cells and fibers; it is traversed by processes from the deep ends of the columnar ciliated cells which line the central canal.