Attribute (Discrete) Control Charts. NP-Chart is an attribute control chart used when plotting: DEFECTIVES BINOMIAL ASSUMPTIONS SATISFIED; CONSTANT (fixed) SAMPLE SIZE (subgroup size) Each observation is independent. Use this chart to develop upper and lower control limits (UCL and LCL) and determine performance of process over time. Choose Stat > Control Charts > Attributes Charts > NP. In Variables, enter Defectives. In Subgroup sizes, enter 500. Click NP Chart Options. On the Tests tab, select 1 point > K standard deviations from center line (Test 1) and K points in a row on same side of center line (Test 2). p and np Control Chart Template. Abstract: Use this set of control charts to monitor defects in a manufacturing process or to control errors in a transactional process. Keywords: Quality Tools; Tools and Templates; Control Chart. np Chart Formulas The np chart is used to evaluate process stability when counting the number or fraction defective. The np chart is useful when it's easy to count the number of defective items and the sample size is always the same. The NP control chart consists of: Vertical axis = the number of defectives for each sub-group; Horizontal axis = the sub-group designation. A sub-group is frequently a time sequence (e.g., the number of defectives in a daily production run where each day is considered a sub- group). k 25 np = no. of lots The control limits are determined by the formula: 112 = 4.6 ± 10.7 LCLnp --1.72 Lot Identification 25 Sample Size (Constann 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 n = 100 Number Defective the Sample) = 112 np-chart What is it? An np-chart is an attributes control chart used with data collected in subgroups that are the same size. Np-charts show how the process, measured by the number of nonconforming items it produces, changes over time. The process attribute (or characteristic) is always described in a yes/no, pass/fail, go/no go form.

## np Chart Formulas The np chart is used to evaluate process stability when counting the number or fraction defective. The np chart is useful when it's easy to count the number of defective items and the sample size is always the same.

Use an np Chart when counting the fraction defective over a constant sample size. Easily create np charts in Excel using QI Macros add-in. p and np Control Chart Template. Abstract: Use this set of control charts to monitor defects in a manufacturing process or to control errors in a transactional np Control Chart Example: Red Beads; Steps in Constructing an np Control Chart ; Small Sample Case; Combining np Charts with Pareto Diagrams. Summary. This procedure generates the NP control chart for the number nonconforming clicking on Open Example Template from the File menu of the P Charts window. Why use it: The Np Control Chart is used to determine if the rate of nonconforming product is stable, and will detect when a deviation from stability has occurred. An np chart is identical to a p chart, except that the Y vertical axis displays the actual count, rather than the ratio. A p-chart is almost always the wiser choice. 10 Mar 1997 DESCRIPTION. An NP chart is a data analysis technique for determining if a measurement process has gone out of statistical control.

### k 25 np = no. of lots The control limits are determined by the formula: 112 = 4.6 ± 10.7 LCLnp --1.72 Lot Identification 25 Sample Size (Constann 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 n = 100 Number Defective the Sample) = 112

np Control Charts. An np control chart is used to look at variation in yes/no type attributes data. There are only two possible outcomes: either the item is defective or it is not defective. The np control chart is used to determine if the number of defective items in a group of items is consistent over time. February 2008 In this Issue: p and np Control Charts Control Limits Binomial Distribution Small Sample Case Summary Quick Links Two control charts used with yes/no type data are the p and np control charts. We usually collect the data and then calculate the average and the control limits, either manually or with software. A control chart begins with a time series graph. A central line (X) is added as a visual reference for detecting shifts or trends – this is also referred to as the process location. Upper and lower control limits (UCL and LCL) are computed from available data and placed equidistant from the central line. Tips for making a Control chart template: Choose the right format: The first step is to choose the perfect format of your control chart. The format differs process to process. Set the limits: It is essential to set the limits of the measures to get the read the process right. The np control chart are used to monitor the number of nonconforming units in samples of inspected units. A nonconforming unit is a product which fails to meet at least one specified requirement. There is a difference between a defect and defective, as there is between a nonconformity and nonconforming unit. Attribute (Discrete) Control Charts. NP-Chart is an attribute control chart used when plotting: DEFECTIVES BINOMIAL ASSUMPTIONS SATISFIED; CONSTANT (fixed) SAMPLE SIZE (subgroup size) Each observation is independent. Use this chart to develop upper and lower control limits (UCL and LCL) and determine performance of process over time.