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Strain rate colour curved anatomical M-mode. The yellow line is drawn from the base of the septum, through the apex and down the lateral wall as can be seen on the small images on the left. The rectangular area then represents the colour M-mode, where the vertical axis is distance along the line, while the horizontal axis is time.
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 ...
It can be measured by simultaneous Doppler echocardiography and M-mode sonography, or better still, by simultaneous phonocardiogram and transmitral Doppler. [2] Prolonged IVRT indicates poor myocardial relaxation. A normal IVRT is about 70 ± 12 ms, and approximately 10 ms longer in people over forty years. [2]
In statistics, the 68–95–99.7 rule, also known as the empirical rule, and sometimes abbreviated 3sr or 3 σ, is a shorthand used to remember the percentage of values that lie within an interval estimate in a normal distribution: approximately 68%, 95%, and 99.7% of the values lie within one, two, and three standard deviations of the mean ...
Mode the most frequent value in the data set. This is the only central tendency measure that can be used with nominal data, which have purely qualitative category assignments. Generalized mean A generalization of the Pythagorean means, specified by an exponent. Geometric mean the nth root of the product of the data values, where there are n of ...
Thus, measurements, normal limits and cut off values are only vendor specific. Due to industrial secrecy, the details of the different algorithms may also be largely unavailable, so a detailed investigation in modelling is difficult. Clinical Applications of Speckle Tracking Technology: Coronary Artery Disease; Myocardial Infarctions
The null hypothesis is that the data set is similar to the normal distribution, therefore a sufficiently small p-value indicates non-normal data. Multivariate normality tests include the Cox–Small test [ 33 ] and Smith and Jain's adaptation [ 34 ] of the Friedman–Rafsky test created by Larry Rafsky and Jerome Friedman .
Some types of normalization involve only a rescaling, to arrive at values relative to some size variable. In terms of levels of measurement, such ratios only make sense for ratio measurements (where ratios of measurements are meaningful), not interval measurements (where only distances are meaningful, but not ratios).