Final answer:
The statement that MRP functions well with a forecast error of plus or minus 10% is false. MRP's effectiveness depends on accurate forecasts and other factors. The provided statistical information about confidence intervals does not directly apply to MRP systems.
Step-by-step explanation:
The statement that MRP works well as long as a forecast is plus or minus 10% can be misleading and is generally considered false. Material Requirements Planning (MRP) is a system for calculating the materials and components needed to manufacture a product, and it relies heavily on accurate input data. While a deviation of plus or minus 10% might be acceptable in some cases, in others, even a small error in forecasting can lead to significant problems such as overstock, stockouts, and missed production schedules. The precision needed in MRP varies with the context of its use, the lead times, the cost of inventory, and the criticality of maintaining tight production schedules.
Regarding the provided information on statistical methods, it does not directly correlate with the functioning of MRP systems. However, it does highlight the importance of confidence levels and sample sizes in statistical analysis. In statistics, the plus-four confidence interval for p method is used to estimate the population mean when the sample size is small, and when a high confidence level is needed. If we took repeated samples, approximately 90 percent of the confidence intervals calculated would contain the true population mean, but this concept is not directly applicable to the accuracy required for MRP systems.