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The sum of independent negative-binomially distributed random variables r 1 and r 2 with the same value for parameter p is negative-binomially distributed with the same p but with r-value r 1 + r 2. This property persists when the definition is thus generalized, and affords a quick way to see that the negative binomial distribution is ...
A VAR with p lags can always be equivalently rewritten as a VAR with only one lag by appropriately redefining the dependent variable. The transformation amounts to stacking the lags of the VAR(p) variable in the new VAR(1) dependent variable and appending identities to complete the precise number of equations. For example, the VAR(2) model
The negative predictive value is defined as: = + = where a "true negative" is the event that the test makes a negative prediction, and the subject has a negative result under the gold standard, and a "false negative" is the event that the test makes a negative prediction, and the subject has a positive result under the gold standard.
In the opposite case, when greater values of one variable mainly correspond to lesser values of the other (that is, the variables tend to show opposite behavior), the covariance is negative. The magnitude of the covariance is the geometric mean of the variances that are in common for the two random variables.
In a Poisson model, "… the random variable is the count response and parameter (lambda) is the mean. Often, λ {\displaystyle \lambda } is also called the rate or intensity parameter… In statistical literature, λ {\displaystyle \lambda } is also expressed as μ {\displaystyle \mu } (mu) when referring to Poisson and traditional negative ...
Every output random variable from the simulation is associated with a variance which limits the precision of the simulation results. In order to make a simulation statistically efficient, i.e., to obtain a greater precision and smaller confidence intervals for the output random variable of interest, variance reduction techniques can be used ...
Let the unknown parameter of interest be , and assume we have a statistic such that the expected value of m is μ: [] =, i.e. m is an unbiased estimator for μ. Suppose we calculate another statistic such that [] = is a known value.
A main assumption in linear regression is constant variance or (homoscedasticity), meaning that different response variables have the same variance in their errors, at every predictor level. This assumption works well when the response variable and the predictor variable are jointly normal. As we will see later, the variance function in the ...