M. KHAMKONG

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Table 1. Estimated 95% coverage probabilities and average widths for poisson means.

Estimated Coverage Probability Estimated Average Width

n Mean (λ) SC MSC WCC AWC SC MSC WCC AWC

15 1 0.9494 0.9494 0.9801 0.9494 0.9804 0.9804 1.2142 0.9494

1.5 0.9423 0.9423 0.9718 0.9423 1.1844 1.1844 1.3914 1.1594

3 0.9570 0.9570 0.9646 0.9570 1.6898 1.6898 1.8277 1.6719

5 0.9436 0.9512 0.9527 0.9436 2.1442 2.1634 2.2629 2.1305

10 0.9551 0.9510 0.9530 0.9461 3.0635 3.0513 3.1269 3.0247

25 1 0.9437 0.9437 0.9847 0.9437 0.7489 0.7489 0.9451 0.7347

1.5 0.9508 0.9508 0.9734 0.9508 0.9209 0.9209 1.0797 0.9091

3 0.9433 0.9502 0.9640 0.9433 1.2864 1.2968 1.4146 1.2782

5 0.9477 0.9530 0.9612 0.9477 1.6660 1.6761 1.7677 1.6596

10 0.9476 0.9511 0.9534 0.9476 2.3517 2.3611 2.4221 2.3472

50 1 0.9454 0.9535 0.9853 0.9454 0.5275 0.5326 0.6689 0.5224

1.5 0.9450 0.9514 0.9738 0.9450 0.6444 0.6492 0.7637 0.6403

3 0.9554 0.9508 0.9655 0.9459 0.9192 0.9151 1.0012 0.9071

5 0.9473 0.9509 0.9600 0.9473 1.1757 1.1804 1.2482 1.1734

10 0.9490 0.9490 0.9560 0.9490 1.6647 1.6647 1.7173 1.6631

100 1 0.9510 0.9510 0.9861 0.9510 0.3741 0.3741 0.4735 0.3723

1.5 0.9571 0.9522 0.9764 0.9475 0.4603 0.4582 0.5412 0.4543

3 0.9471 0.9506 0.9648 0.9471 0.6438 0.6463 0.7077 0.6428

5 0.9489 0.9489 0.9602 0.9489 0.8324 0.8324 0.8828 0.8316

10 0.9475 0.9491 0.9541 0.9475 1.1750 1.1770 1.2120 1.1744

From the simulation results (Table 1), the estimated 95%

coverage probabilities of AWC close to the nominal level

in all cases and are similar to the SC and MSC interval.

Morever, in many cases of small mean and small to mod-

erate sample sizes such as

= 1, 1.5 and n = 15, 25,

AWC seems to be preferable in the sence that their

average width is shorter than others. However, when the

mean and sample size are both increase, the average

widths AWC interval are similar to other confidence in-

tervals.

Therefore, it can be recommended that the AWC in-

terval is more likely to be outperformed for small mean

Poisson and small to moderate sample sizes. In addition,

the AWC formula is simple and easy to compute. It

should be considered that a sample observation is drawn

from a Poisson distribution.

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