Type Of Control Chart

Control charts are simple but very powerful tools that can help you determine whether a process is in control (meaning it has only random, normal variation) or out of control (meaning it shows unusual variation, probably due to a "special cause").

Continuous data usually involve measurements, and often include fractions or decimals. Weight, height, width, time, and similar. All Measurements are all continuous dataIf you're looking at measurement data for individuals, you would use an I-MR chart. If your data are being collected in subgroups, you would use an Xbar-R chart if the subgroups have a size of 8 or less, you would use  an Xbar-S chart if the subgroup size is larger than 8. If you have attribute data, you need to determine if you're looking at proportions or counts. If it's proportions, you'll typically be counting the number of defective items in a group, thus coming up with a "pass-fail" percentage. In this case, you would want to use a P chart.(P-proportion). If you're measuring the number of defects per unit, you have count data, which you would display using a U chart (U-units or Nos).