My fascination with statistics started in the late 7os when i was a young student of Psychology. I was working with a government computer agency as computer operator then and many time to spare to read during my break. One day, a beautiful office mate asked me a favor if i can solve her statistics assignment which i readily accepted given her irresistible charm. She requested me to teach her about the concept of normal curve distribution and standard score (z-score). There i begun to understand that a normal curve is divided into 2 parts — 50% below the mean and 50% above the mean. Simple. Each half is divided into 4 parts of .13%, 2.14%, 13.59%, and 34.13% which would total 49.99 or 50%. The center being the average or what we call the mean. One standard deviation + or – the mean would be 68.26 (that is 34.13% + 34.13%). Two standard deviations above and below the mean would equal to 95.44% (i.e., 13.59 + 34.16+34.16 + 13.59). Three standard deviations below and above the mean would be 99.72%. The values represented by percentage are your probability values given a normal distribution. To get a clearer understanding of what i am saying, please look at the figure below.
My next blog will be about the concept of descriptive statistics and dispersion. Hasta luego!