Contents
What is log normality?
In probability theory, a log-normal (or lognormal) distribution is a continuous probability distribution of a random variable whose logarithm is normally distributed. A log-normal process is the statistical realization of the multiplicative product of many independent random variables, each of which is positive.
What is another name for the Z distribution?
Standard Normal distribution
Definition. The Standard Normal distribution, also known as the Z distribution, is one particular form of the Normal distribution in which the mean is zero (i.e., 0) and the variance is unity (i.e., 1).
What does the area under the normal distribution mean?
The normal distribution is a continuous probability distribution that is symmetrical on both sides of the mean, so the right side of the center is a mirror image of the left side. The area under the normal distribution curve represents probability and the total area under the curve sums to one.
Why is the normal distribution called the bell curve?
For a perfectly normal distribution the mean, median and mode will be the same value, visually represented by the peak of the curve. The normal distribution is often called the bell curve because the graph of its probability density looks like a bell.
Which is the mirror image of a normal distribution?
A normal distribution has a bell-shaped curve and is symmetrical around its center, so the right side of the center is a mirror image of the left side. Most of the continuous data values in a normal distribution tend to cluster around the mean, and the further a value is from the mean, the less likely it is to occur.
What kind of statistical test is normal distribution?
The most powerful (parametric) statistical tests used by psychologists require data to be normally distributed. If the data does not resemble a bell curve researchers may have to use a less powerful type of statistical test, called non-parametric statistics.