A bell-shaped continuous random variable X , with center at the mean value ( μ ) and distance from the center to the inflection points of the bell curve given by the standard deviation ( σ ) We write X ~ N ( μ , σ ) . If the mean value is 0 and the standard deviation is 1, the random variable is called the standard normal distribution, and it is denoted with the letter Z

Information that is known about the distribution (for example, known standard deviation) The pdf is symmetrical about its mean of zero.

hypothesis — a statement about the value of a population parameter; in the case of two hypotheses, the statement assumed to be true is called the null hypothesis (notation H 0 ) and the…. hypothesis testing — based on sample evidence, a procedure for determining whether the hypothesis stated is a reasonable statement and should not be rejected, or is unreasonable and should be rejected. standard deviation — a number that is equal to the square root of the variance and measures how far data values are from their mean; notation: s for sample standard deviation and σ for population…. mean value — 0 and the standard deviation is 1, the random variable is called the standard normal distribution, and it is denoted with the letter Z.