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Q Function Calculator

Q Function Calculator

Q Function Calculator

Q Function is the probability that at least 1 element of the list will contain a value of the function. It is the sum of all the probability of the random variable on the list having the value. It is named for its relation to the Q function, a general function for probabilities on lists of numbers.

Value

To compute a left-tail probability, select $P(X \lt x)$ from the drop-down box, enter a numeric $x$ value in the blue box and press "Tab" or "Enter" on your keyboard. The probability $P(X \lt x)$ will appear in the pink box. Select $P(X \gt x)$ from the drop-down box for a right-tail probability.

The CDF for the normal distribution gives you the probability that a normal random variable takes a value equal to or smaller than x. The Q function is the complement of this; In other words, it’s the probability a normal random variable takes a value greater than x. (Source: www.statisticshowto.com)

Example

Calculating the function by hand is relatively simple: find the CDF, and subtract from one. Some software programs find the Q function directly. For example, In MATLAB, the syntax is y = qfunc(x). If your software doesn’t, find the CDF and subtract from one.

The conditional expected log-likelihood, used in calculating the E-step in the EM algorithm (see Gupta and Chen 2011 for an example), (Source: www.statisticshowto.com)

Random

The CDF for the normal distribution gives you the probability that a normal random variable takes a value equal to or smaller than x. The Q function is the complement of this; In other words, it’s the probability a normal random variable takes a value greater than x.

returns the output of the Q function for each element of the real-valued input. The Q function is (1 – f), where f is the result of the cumulative distribution function of the standardized normal random variable. For more information, see Algorithms. (Source: www.mathworks.com)

 

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