Search results
Results From The WOW.Com Content Network
Normality, and abnormality, can be characterized statistically. Related to the previous definition, statistical normality is usually defined it in terms of a normal distribution curve, with the so-called 'normal zone' commonly accounting for 95.45% of all the data.
The simplest case of a normal distribution is known as the standard normal distribution or unit normal distribution. This is a special case when μ = 0 {\textstyle \mu =0} and σ 2 = 1 {\textstyle \sigma ^{2}=1} , and it is described by this probability density function (or density): φ ( z ) = e − z 2 2 2 π . {\displaystyle \varphi (z ...
For example, suppose that scale scores are found to have a mean of 23.5, a standard deviation of 4.2, and to be approximately normally distributed. Then sten scores for this scale can be calculated using the formula, () +. It is also usually necessary to truncate such scores, particularly if the scores are skewed.
The term "curve" refers to the bell curve, the graphical representation of the probability density of the normal distribution, but this method can be used to achieve any desired distribution of the grades – for example, a uniform distribution.
The most prominent example of a mesokurtic distribution is the normal distribution family, regardless of the values of its parameters. A few other well-known distributions can be mesokurtic, depending on parameter values: for example, the binomial distribution is mesokurtic for p = 1 / 2 ± 1 / 12 {\textstyle p=1/2\pm {\sqrt {1/12}}} .
The figure illustrates the percentile rank computation and shows how the 0.5 × F term in the formula ensures that the percentile rank reflects a percentage of scores less than the specified score. For example, for the 10 scores shown in the figure, 60% of them are below a score of 4 (five less than 4 and half of the two equal to 4) and 95% are ...
Zebra, a medical slang term referring to a rare condition that may go undiagnosed or misdiagnosed due to medical staff identifying its symptoms as that of as a much more common (and often less severe) condition; Don't Look Up
A plot of normal distribution (or bell-shaped curve) where each band has a width of 1 standard deviation. If the threshold is 2 standard deviations above the mean of the latent variable, then about 2.4% of the population would have the trait.