Suspicious measurements

Note any unusual occurrences, even if they indicate some laziness or inattentiveness on your part. Despite aU earnest attempts to keep an experiment from going awry, the complexity of most experiments conspires to introduce error or accidents into all observations. (It s far better to acknowledge an erroneous or suspicious measurement than to send later readers (including yourself) off on a series of experiments to follow up on a misleading observation that appears in your notebook without comment.)... 

If a low sodium concentration is suspicious, measure the serum osmolality. Know ing the glucose and urea concentration, the calculated osmolality can also be obtained. If the two results differ (that is, if there is a significant osmolal gap), the measured. sodium... 

Update the state vector and the associated covariance matrix using the measurement obtained from step (5) using Eq. 13 to Eq. 15. If all Nq elements of the (A +l)th data points are suspicious measurements, yi+iii+i = yjt+iiit and Syjt+iiit+i = Sy +ii. ... 

Since some earlier work based on anisotropic elasticity theory had not been successful in describing the observed mechanical behaviour of NiAl (for an overview see [11]), several studies have addressed dislocation processes on the atomic length scale [6, 7, 8]. Their findings are encouraging for the use of atomistic methods, since they could explain several of the experimental observations. Nevertheless, most of the quantitative data they obtained are somewhat suspicious. For example, the Peierls stresses of the (100) and (111) dislocations are rather similar [6] and far too low to explain the measured yield stresses in hard oriented crystals. 

If H0 is rejected, a two-stage procedure is initiated. First, a list of candidate biases and leaks is constructed by means of the recursive search scheme outlined by Romagnoli (1983). All possible combinations of gross errors (measurement biases and/or process leaks) from this subset are analyzed in the second stage. Gross error magnitudes are estimated simultaneously for each combination and chi-square test statistic calculations are performed to identify the suspicious combinations. We will now explain the stages of the procedure. 

DR. NORTON I read that paper with some care. I am afraid I am not convinced by the result. The cobalt and iridium results are believable. They have been carefully measured and they agree with the general trend. The rhodium result is not well measured, and I am inclined, therefore, to be suspicious of the fact that it doesn t fit the general trend. 

Rejection. The first strategy Is to remove the suspicious datum from the data. Then, the analysis and the conclusions to be drawn are based only on the remaining values. This certainly Is the way to deal with outliers which result from human errors, gross errors of measurement or something similar (Figure lb). 

For cells with /1-galactosidase deficiency (GM1 gangliosidosis or Morquio type as well as I-cell disease), the measured enzyme activity will be significantly lower than the true enzyme activity. In addition, cases of multiple sulfatase deficiency will also show low N-acetylgalactosamine-6-sulfatase activity. Therefore, arylsulfatase A or another sulfatase, as well as /1-galactosidase activities should also be determined in case of suspicious results. To exclude poor sample quality, the determination of a-mannosidase is recommended. 

If the patient is actually asymptomatic, but has a family history of acute porphyria or prior symptoms suspicious of acute porphyria, hydroxymethylbilane synthase (HMBS) activity, plasma scanning, and fecal porphyrins should be measured. These tests will reveal AIP, P V, and HC. As a small percentage of AIP families exhibit normal HMBS activity, PBG in a urine sample can be added. PBG determination can also performed as a first choice, if an acute porphyria is suspected. But if normal, it does not exclude acute porphyrias in asymptomatic phases. Furthermore, the existence of an acute porphyria is only proved if the value exceeds at least five times the upper limit of normal. 

The activity of a very weak active mutant measured by steady state kinetics could result from traces of a wild-type or more active mutant in the preparation either as a contaminant or because of natural errors of misincorporation. The error rate in protein biosynthesis can be as high as one part in 100 or one part in 1000.10 The presence of a small amount of wild-type enzyme in an inactive mutant would give a low value of kcat (which is directly proportional to the concentration of wild type) but the KM value for the wild-type enzyme. Thus, the finding of a low value of kcat and the wild-type KM for a mutant is very suspicious. 

The smaller the ratio of the standard deviation to the average value, the better the precision. However, there is no absolute standard that defines good precision or bad precision. In general, you should become increasingly suspicious of measurements as the ratio of standard deviation to the average value increases. For an experienced analytical chemist, working with a well-known system, this ratio will typically be less than 0.1%, but this level of precision is unlikely in a clinical setting. 

But this analogy is suspicious. In mechanics ideal plane serves as a benchmark of description, and measurements and calculations do tell us exactly how far a particular system is from the ideal. Epistemically ideal conditions are not like that. 

Example A young person died under suspicious circumstances with suspected alcohol poisoning and there was uncertainty over the validity of the blood specimen, prompting quantitative measurement of alcohol in urine. 

The determination of odors in water was addressed previously under the discussion on taste. Odors in air are determined differently. They are quantitatively measured by convening a panel of human evaluators. These evaluators are exposed to odors that have been diluted with odor-free air. The number of dilutions required to bring the odorous air to the minimum level of detectable concentration by the panel is the measure of odor. Thus, if three volumes of odor-free air is required, the odor of the air is three dilutions. It is obvious that if these evaluators are subjected to the odor several times, the results would be suspicious. For accurate results, the evaluators... 

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