Sampling inspection is one of the quality control tools used in industry to help keep the quality of the products at satisfactory level while at the same time having the cost in control. When using acceptance sampling inspection, a decision on whether the lot of items is to be accepted or rejected is based on results of inspecting a sample of items from the lot. Acceptance sampling plans which minimize the mean inspection cost per lot of the process average quality when the remainder of rejected lots is inspected were originally designed by Dodge and Romig for the inspection by attributes. Sampling plans for the inspection by variables were then proposed and it has been shown that such plans may be more economical than the corresponding attributes sampling plans. We recall the calculation and economic performance evaluation of the variables sampling plans, show how further improvements in inspection cost could be achieved using EWMA-based statistic and we comment on some of the possibilities available for calculation and evaluation of the plans in R extension package LTPDvar.