Whatw~r type of statistical design is used for a study, the problem of sample size must be faced. This aspect, which causes considerable difficulty for researchers, is perhaps the most common reason for consulting a statistician. There are also, however, many who give little thought to sample size, choosing the most convenient number (20, 50, 100, etc) or time period (one month, one year, etc) ...

In this research, the main parameters of the multivariate CUSUM control chart (the reference value k , the control limit H , the sample size n , and the sampling interval h ) are determined by minimizing the Lorenzen-Vance cost function (Lorenzen TJ, Vance LC. The economic design of control charts: A unified approach. Technometrics 28: 3-10, 1986 [1],) in which the external costs of employing t...

Shewhart X¯ control charts commonly used for monitoring the mean of a process may be inaccurate or perform poorly when subgroup size is small distribution variable skewed. Truncated saddlepoint distributions can increase accuracy estimated limits by including higher order moments/cumulants in their approximation, yet this not exist lower tail, and thus limit exist. We introduce novel modificati...

One of the major issues in planning a research is the decision as to how large a sample and the method to be employed to select the estimated sample in order to meet the objective of the research. Sampling is an essential tool for research in medicine. A good number of the medical literature while reporting their sampling method go by stating that the sample was collected by random sampling and...

In today's highly competitive industrial environment due to fast technology development, quality practitioners will to detect out-of-control situations and take actions whenever is necessary as soon as possible. Accordingly, new statistical procedures have been enhanced incessantly both to handle high yield processes along with looking for methods of minimizing all quality cost. CCC-r chart, th...

Background and aims: Nowadays, hypnosis has opened its position in the medical community. Based on controlled trials, hypnosis has been superior compared to other interventional procedures to reduce acute pain. This investigation aims to determine the effectiveness of hypnosis in the treatment of pain and enhancing mental performance in Iran, using the meta-analysis method. <br...

The main purpose in many randomized trials is to make an inference about the average causal effect of a treatment. Therefore, on a binary outcome, the null hypothesis for the hypothesis test should be that the causal risks are equal in the two groups. This null hypothesis is referred to as the weak causal null hypothesis. Nevertheless, at present, hypothesis tests applied in actual randomized t...