# Checkpoint

Enumerative study is the study and analysis of a static population while analytic study is the analysis of a dynamic time series. For a descriptive statistics, which is analyzing existing data, the enumerative study is suitable, while for hypothesis testing on population mean and tie series analysis, an analytic study is more appropriate. The analysis of a static population is referred to as an enumerative study, and the analysis of a dynamic time series is referred to as an analytic study.

Enumerative studies are more appropriate for descriptive statistics and hypothesis testing on the population mean considering the process is stable. Analytic studies are more appropriate for time-series analysis. (See p. 506) 4. (TCO 12) Explain the difference between Type I and Type II errors in the context of a control chart Relative to the control chart, making a Type error means assuming the process is out of control when it isn’t, thinking a plot point is outside the control limits when in fact the process is still in control.

As a result, someone would try to fix a problem that is not there and disturb a process that actually is in control. Making a Type II error means assuming the process is in control when it actually is not, thinking a plot point is within the control limits when in fact the process is out of control. As a result, someone would neglect to fix an existing problem, assuming it is not there and the process would remain out of control. A Type error concerns taking action when no action is needed.

Some patterns that appear to indicate an out-of-control process occur merely by chance and do not represent a process that has shifted. A Type II error relates to not taking action when the process has actually changed. The typical cause of such an error is wide control limits. For instance, a point that falls just inside three sigma control limits implies nothing has changed, but in reality such a point may indicate a process shift. Narrower control limits, such as two sigma limits, would have flagged the single point outside the limits as representing an out-of-control state and requiring action.

Wider control limits increase Type II errors and decrease Type I errors. (See up. 701-703) 5. (T CO 12) What conditions support the use of a control chart for individuals. Discuss any limitations associated with the chart use. The normal distribution, by definition, will place the individual x control limits at plus and minus 3 times the process sigma value from the process mean, without regard to whether your process can logically operate there.

Of course, the calculations have no advance knowledge of your process, and in this case assumes that your process approximately follows the conditions of a normal distribution. A control chart for individuals can be used when the sample size is limited to one. This is usually due to an abundance of individually measured items that an be readily obtained from, say, process monitoring equipment, or due to costly tests that limit sample size to a single item.