The standard normal distribution :
High-Yield Explanation
The standard detion in a standard normal curve is 1.0. The variance (SD2) is thus also one. Ref: Park's Textbook Of Preventive And Social Medicine By K. Park, 19th Edition, Page 702; Park's Textbook Of Preventive And Social Medicine By K. Park, 18th Edition, Page 647; Methods in Biostatistics: For Medical Students and Research Workers By BK Mahajan, 6th Edition, Page 68