Archive for February 2016
P Chart with SigmaXL
What is a P Chart? The P chart plots the percentage of defectives in one subgroup as a data point. It considers the situation when the subgroup size of inspected units is not constant. The underlying distribution of the P-chart is binomial distribution. P Chart Equations Data Point: Center Line: …
Read MoreU Chart with SigmaXL
What is a U Chart? The U chart is a type of control chart used to monitor discrete (count) data where the sample size is greater than one, typically the average number of defects per unit. Defect vs. Defective Remember the difference between defect and defective? A defect of a unit is the unit’s characteristic…
Read MoreXbar R Chart with SigmaXL
What is a Xbar R Chart? The Xbar R chart is a control chart for continuous data with a constant subgroup size between two and ten. [unordered_list style=”star”] The Xbar chart plots the average of a subgroup as a data point. The R chart plots the difference between the highest and lowest values within a…
Read MoreIR Chart with SigmaXL
What is an IR Chart? The IR chart (also called individual-moving range chart or I-MR chart) is a popular control chart for continuous data with subgroup size equal to one. [unordered_list style=”star”] The I chart plots an individual observation as a data point. The MR chart plots the absolute value of the difference between two…
Read MoreFractional Factorial Designs with SigmaXL
What Are Fractional Factorial Experiments? In simple terms, a fractional factorial experiment is a subset of a full factorial experiment. [unordered_list style=”star”] Fractional factorials use fewer treatment combinations and runs. Fractional factorials are less able to determine effects because of fewer degrees of freedom available to evaluate higher order interactions. Fractional factorials can be used…
Read MoreLogistic Regression with SigmaXL
What is Logistic Regression? Logistic regression is a statistical method to predict the probability of an event occurring by fitting the data to a logistic curve using logistic function. The regression analysis used for predicting the outcome of a categorical dependent variable, based on one or more predictor variables. The logistic function used to model…
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