Standard Deviation (Volatility) Introduction. Standard deviation is a statistical term that measures the amount of variability or dispersion around an average. Standard deviation is also a measure of volatility. Generally speaking, dispersion is the difference between the actual value and the average value. The larger this dispersion or variability is, the higher the standard deviation. The smaller this dispersion or variability is, the lower the standard deviation.
MRI image showing a typical meningioma tumor. A meningioma is a tumor that arises from a layer of tissue (the meninges) that covers the brain and spine. Meningiomas grow on the surface of the brain (or spinal cord), and therefore push the brain away rather than growing from within it. Most are considered âbenignâ because they are slow-growing with low potential to spread. Meningioma tumors can become quite large. Diameters of 2 inches (5 cm.) are not uncommon.
A hemangioma is a benign (noncancerous) tumor made up of blood vessels. There are many types of hemangiomas, and they can occur throughout the body, including in skin, muscle, bone, and internal organs.Most hemangiomas occur on the surface of the skin or just beneath it.one hemangioma. The hemangiomas that occur in bones typically occur in the skull or spine and are most common in people who are 50 to 70 years of age. Capillary and cavernous types are the most common hemangiomas found in bone. They can grow on the surface or deeper into the center canal of a bone.