External studentization

Ingold s colleagues and proteges frequently have noted that his later penchant for combining physical methods with chemical techniques was presaged in a youthful precocity in physics. He began serious scientific studies at Hartley University, Southampton, as an external student of the University of London. He was "better at physics than chemistry," he later recalled, but his enthusiasm for chemistry was fired by a gifted teacher, D. R. Boyd.5... 

Upper bounds for externally studentized residuals have not been developed. Externally studentized residuals are distributed as a Student s t-distribution with n—p—1 degrees of freedom. Thus in the case of a single outlier observation, a quick test would be to compare the value of the external studentized residual to the appropriate t-distribution value, although as Cook and Weisberg (1999) point out, because of issues with multiplicity a more appropriate comparison would be Student s t-distribution with a/n critical value and n—p—1 degrees of freedom. In general, however, a yardstick of 2 or 2.5 is usually used as a critical value to flag suspect observations. 

Hence, raw residuals are often standardized by some quantity, usually its standard deviation, to account for the unequal variance of the residuals. If the estimate of the standard deviation is based on the observation in question the method is called internal studentization, but if the observation is not included in the estimate of the standard deviation, then the method is called external studentization. Studentized residuals can be estimated... 

Classical statistical tests can be applied mainly to validate regression models that are linear with respect to the model parameters. The most common empirical models used in EXDE are linear models (main effect models), linear plus interactions models, and quadratic models. They all are linear with respect to the p>arameters. The most useful of these (in DOE context) are 1) t-tests for testing the significance of the individual terms of the model, 2) the lack-of-fit test for testing the model adequacy, and 3) outlier tests based on so-called externally studentized residuals, see e.g. (Neter et. al., 1996). 

The externally studentized residual is also termed jackknifed residual. 

The externally studentized residual is scale invariant. Com-monly, an outlier is detected if tj- > 2. 

Attends the Catholic Academy at Toulouse as external student. Converts to Catholicism. xlv ... 

As an interesting variation on this experiment, one can try reading in the experimental data from an external file. The student should do some outside... 

Eatty acids from commercial fats and oils, such as peanut oil, are extracted with methanolic NaOH and made volatile by derivatizing with a solution of methanol/BE3. Separations are carried out using a capillary 5% phenylmethyl silicone column with MS detection. By searching the associated spectral library students are able to identify the fatty acids present in their sample. Quantitative analysis is by external standards. 

Based on a comprehensive review of chemistiy education literature, Wu and Shah (2004) suggest live principles for designing multimedia tools that help students understand concepts and develop their representational skills (e.g., making translations among representations, creating representations to externalize thinking, and... 

In this chapter, we present an attempt to put these ideas into practice that has three components. First, we use a Model of Modelling , an external representation of the mental processes that we postulate to be undergone as a person forms a model. Second, this model is exemplified by its apphcation to the design of a teaching sequence about a key topic in chemistry, the imderstanding of which requires fluency of mental movement between the three levels of representation. Lastly, this application is implemented in such a way that the processes of students thought taking place can be monitored. 

Import the table of measured data, which actually originate from a student experiment, into the program from the external file ESTERdat.txt (Menu Model/ Datasets). Data are listed as time (min) versus titrated volume (mL). Modify the plot window correspondingly (Double click. Now, adjust Integration Time, STOPTIME, to see all data points. Modify kl and k2 manually to obtain an optimal fit of measured data (MLtitrated) to experimental data ( ESTERdat). 

Full details are given in the HSE information leaflets obtainable as given below see also RSC (1996). Before the commencement of any work that involves or creates substances that may be hazardous to health, the risks, control measures and disposal procedures to be adopted should be assessed and recorded on appropriate forms. These should be signed by the assessor, and where appropriate by the student, and then countersigned by the Head of Department. One copy should be kept for local reference in the laboratory, with the original filed centrally for inspection by external inspectors. Only after this, should any new chemicals be ordered by a designated person (or deputy) who should check that the COSHH form has been duly completed. COSHH guidelines may be summarized in seven points ... 

There are two types of analytical information as regards its target and origin. External analytical information originates from a bidirectional relationship between the analytical chemist and a) society, (b) the body to which the laboratory is answerable, (c) other scientific and technical areas, id) literature sources (which the analytical chemist uses and expands), and (e) students. On a lower level, subordinate to external information, internal information originates from a uni- or bidirectional relationship between the analytical chemist and a) instruments (and apparatuses) and (b) computers, in addition to the information transferred between interfaced instruments and between computers and instruments. 

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