Statistics for Six Sigma Green Belts with Minitab and JMP

5.6. The Normal Distribution

The normal distribution is a continuous bell-shaped distribution used for measurement data. Continuous distributions differ from discrete distributions such as the binomial and Poisson distributions in the following ways:

1. Any value within the range of the variable can occur, rather than just specific (i.e., integer) values. For example, cycle time can be measured to as many decimal places as are appropriate.

2. The probability of occurrence of a specific value of X is zero. For example, the probability of a cycle time being measured at exactly 3.0000000000 seconds approaches zero as the number of digits to the right of the decimal point gets larger.

3. Probabilities can be computed by cumulating an area under a curve. For ...