ABEV2 {gofIG} | R Documentation |
This function computes the second test statistic of the goodness-of-fit tests for the inverse Gaussian family due to Allison et al. (2022). Two different estimation procedures are implemented, namely the method of moment and the maximum likelihood method.
ABEV2(data, a = 10, meth = "MME")
data |
a vector of positive numbers. |
a |
positive tuning parameter. |
meth |
method of estimation used. Possible values are |
The numerically stable test statistic for the second Allison-Betsch-Ebner-Visagie test is defined as:
ABEV2_{n,a} = \frac{1}{4n} \sum_{j,k=1}^{n} \left( \hat{\varphi}_n + \frac{3}{Y_{n,j}} - \frac{\hat{\varphi}_n}{Y_{n,j}^2} \right) \left( \hat{\varphi}_n + \frac{3}{Y_{n,k}} - \frac{\hat{\varphi}_n}{Y_{n,k}^2} \right) \tilde{h}_{1,a}(Y_{n,j}, Y_{n,k})
- 2 \left( \hat{\varphi}_n + \frac{3}{Y_{n,j}} - \frac{\hat{\varphi}_n}{Y_{n,j}^2} \right) \tilde{h}_{2,a}(Y_{n,j}, Y_{n,k})
- 2 \left( \hat{\varphi}_n + \frac{3}{Y_{n,k}} - \frac{\hat{\varphi}_n}{Y_{n,k}^2} \right) \tilde{h}_{2,a}(Y_{n,k}, Y_{n,j})
+ 4 \frac{\sqrt{\pi}}{a} \Phi \left( - \sqrt{2a} \max(Y_{n,j}, Y_{n,k}) \right),
with \hat{\varphi}_n = \frac{\hat{\lambda}_n}{\hat{\mu}_n}
, where \hat{\mu}_n,\hat{\lambda}_n
are consistent estimators of \mu, \lambda
, respectively, the parameters of the inverse Gaussian distribution. Furthermore Y_{n,j} = \frac{X_j}{\hat{\mu}_n}
, j = 1,...,n
, for (X_j)_{j = 1,...,n}
, a sequence of independent observations of a positive random variable X
.
The functions \tilde{h}_{i,a}(s,t)
, i = 1,2
, are defined in Allison et al. (2022), section 5.1, and \Phi
denotes the distribution function of the standard normal distribution.
The null hypothesis is rejected for large values of the test statistic ABEV2_{n,a}
.
value of the test statistic.
Allison, J.S., Betsch, S., Ebner, B., Visagie, I.J.H. (2022) "On Testing the Adequacy of the Inverse Gaussian Distribution". LINK
ABEV2(rmutil::rinvgauss(20,2,1),a=10,meth='MLE')