TECHNIQUE 54 Cause Effect Matrix

Use a Cause Effect Diagram (Technique 53) to document all the important causal relationships in the system. Then prioritize these relationships using a Cause Effect Matrix (Technique 54). These then become the initial focus of an attempt to trim the system using a trimming worksheet. 

Use a Cause Effect Matrix (Technique 53) to determine the relationship between the design s inputs and outputs. If you understand how each input affects the output, both individually and in combination, you can improve your design performance and reduce variability. 

While the purpose of Design Scorecards is to prevent problems, defects, and errors through superior design, they also enable better problem detection after a new solution (design) is implemented. If you are in detect-and-fix mode, any number of process-optimization techniques may help, such as Process Behavior Charts (Technique 52), Cause Effect Matrix (Technique 54), Mistake Proofing (Technique 49), and Design of Experiments (Technique 50). 

Factors are the inputs you will vary during the experiment to determine the effect on the response. Use a Cause Effect Matrix (Technique 54) to help you identify all possible factors that contribute to the responses you listed in step 1. Then, narrow down the list based on cost and time constraints. Typically, two to seven factors work best. 

Continue to drill down on each possible cause, asking, Why When you finish, you will have narrowed down the potential causes to the main root causes. These can be further investigated using a Cause Effect Matrix (Technique 54) to determine which inputs have the greatest impact on customer-centric outputs and, thus, need to be addressed to maintain customer expectations. 

With an optimized innovation ready for the market, it s time to improve and transition the project to its owners for ongoing operation. Use the Process Behavior Charts and Control Plan techniques during and after this transition. Also use the Cause Effect Diagram and Cause Effect Matrix to diagnose, solve, or at least mitigate any implementation problems encountered. 

Scenario In the DVD-by-mail example from the Cause Effect Diagram (Technique 53), we looked for the root causes (inputs) contributing to customer dissatisfaction. We can also use a Cause Effect Matrix to discover... 

Bombardment of a liquid surface by a beam of fast atoms (or fast ions) causes continuous desorption of ions that are characteristic of the liquid. Where the liquid is a solution of a sample substance dissolved in a solvent of low volatility (often referred to as a matrix), both positive and negative ions characteristic of the solvent and the sample itself leave the surface. The choice of whether to examine the positive or the negative ions is effected simply by the sign of an electrical potential applied to an extraction plate held above the surface being bombarded. Usually, few fragment ions are observed, and a sample of mass M in a solvent of mass S will give mostly [M + H] (or [M - H] ) and [S -I- H]+ (or [S - H] ) ions. Therefore, the technique is particularly good for measurement of relative molecular mass. 

Sources of Error. pH electrodes are subject to fewer iaterfereaces and other types of error than most potentiometric ionic-activity sensors, ie, ion-selective electrodes (see Electro analytical techniques). However, pH electrodes must be used with an awareness of their particular response characteristics, as weU as the potential sources of error that may affect other components of the measurement system, especially the reference electrode. Several common causes of measurement problems are electrode iaterferences and/or fouling of the pH sensor, sample matrix effects, reference electrode iastabiHty, and improper caHbration of the measurement system (12). 

At present, inductively coupled plasma mass spectrometry provides a unique, powerful alternative for the determination of rare earths in natural samples [638,639]. Nevertheless, its application to the determination of rare earths at ultratrace concentration level in seawater is limited, because highly saline samples can cause both spectral interferences and matrix effects [640]. Therefore, a separation of the matrix components and preconcentration of the analytes are prerequisites. To achieve this goal, many preconcentration techniques have been used, including coprecipitation with... 

A substantial number of papers have been published between the 60s and the 90s on the determination of inorganic analytes by CL-based techniques. The application of established methods to the analysis of inorganic compounds involves the areas of environmental, geographical, and biological sciences. Although many efforts have been undertaken in the past years, there still remains a challenge to apply CL-based techniques to routine analysis of inorganic elements, as the complex matrix of a real sample may cause unexpected effects on CL emission. 

During a single run, which may take all day if a large number of samples are to be analyzed, the instrument may drift from its optimum settings. To detect this drift in solution-based techniques, and also to compensate for some matrix effects, a known amount of an element may be added to each sample before analysis. This internal standard (also called a spike) is added to all the samples and blanks, with the exception of the instrument blank (which is defined as zero concentration for all elements see below). It is important that the element (or isotope) chosen as the spike is not an element which is to be determined in the samples, and preferably which does not occur naturally in the samples. It must not be an element which will cause, or suffer from, interference with the other elements to be determined. In solution ICP-MS,... 

Matrix effects in the analysis of nutrients in seawater are caused by differences in background electrolyte composition and concentration (salinity) between the standard solutions and samples. This effect causes several methodological difficulties. First, the effect of ionic strength on the kinetics of colorimetric reactions results in color intensity changes with matrix composition and electrolyte concentration. In practice, analytical sensitivity depends upon the actual sample matrix. This effect is most serious in silicate analysis using the molybdenum blue method. Second, matrix differences can also cause refractive index interference in automated continuous flow analysis, the most popular technique for routine nutrient measurement. To deal with these matrix effects, seawater of... 

---