Significance of data

Interpretation. The process whereby one determines the clinical meaning or significance of data after the relevant statistical analyses have been performed. These processes often involve developing an explanation of the data that are being evaluated. 

Statistical methods frequently are used to give a yes-or-no answer to a particular question concerning the significance of data. The answer is qualified by a confidence level indicating the degree of certainty of the answer. This procedure is known as hypothesis testing ... 

Although many problems exist in regard to the physical significance of data obtained by compression testing, this method is an easy and fast procedure for the determination of agglomerate strength for quality control in industrial applications, for example. 

The significance of data points in upper part of Fig. 8b is difficult to access. 

The influence of gonadal hormones upon uterine fibrinolytic activity has recently been reviewed by Astrup [280]. Publications have appeared on the effects of oral contraceptives and of their constituents upon blood platelet adhesiveness (see inter alia [281, 282]), Both oral contraceptives and oestrogens may increase platelet sensitivity to aggregating agents, but the pathological significance of data obtained undo- such artificial test conditions is still presumptive and equivocal. 

Information available from national, industry and insurance company sources. Information available within an organisation systems for recording, storing, retrieving, and analysing data significance of data on sick absence, damage accidents and product complaints. 

This section will look at formation and fluid data gathering before significant amounts of fluid have been produced hence describing how the static reservoir is sampled. Data gathered prior to production provides vital information, used to predict reservoir behaviour under dynamic conditions. Without this baseline data no meaningful reservoir simulation can be carried out. The other major benefit of data gathered at initial reservoir conditions is that pressure and fluid distribution are in equilibrium this is usuaily not the case once production commences. Data gathered at initial conditions is therefore not complicated... 

Availability of a representative set of data examples. Such a set may significantly simplify construction of any automatic interpretation system. The example data is usually obtained from calibration pieces, however, they usually represent only the most common defects and are usually expensive to manufacture. Recently more and more data is stored as digital inspection records, unfortunately the stored data is rarely fully classified, as this would increase the cost of inspection (usually only the serious defects are given full description in the reports). 

Repeatability. This refers to two aspects of inspection similarity between objects that are inspected and possibility of maintaining constant inspection conditions (settings) for all the inspections performed. Obviously, interpretation of data in repeatable conditions is significantly simplified. Usually, inspection during or after manufacturing process will be repeatable. Another example of repeatable inspection is inspection of heat exchangers in power nuclear plants, inspection of aircrafts as these are well standardised. However, a large part of the NDT inspection done is not repeatable. 

Significant reduction in the time needed to collect a sufficient number of data ... 

When plotted according to the linear form of the BET equation, data for the adsorption of N2 on Graphon at 77 K give an intercept of 0.004 and a slope of 1.7 (both in cubic centimeters STP per gram). Calculate E assuming a molecular area of 16 for N2. Calculate also the heat of adsorption for the first layer (the heat of condensation of N2 is 1.3 kcal/mol). Would your answer for Vm be much different if the intercept were taken to be zero (and the slope the same) Comment briefly on the practical significance of your conclusion. 

CTfilcs originated in the time of punched cards and therefore their format is quite restrictive. For example, blanks usually arc significant and several consecutive spaces cannot simply be replaced by a single one. Spaces may correspond to missing entries, empty character positions within entries, spaces between entries, or 2cros in the case of numerical entries. Thus, eveiy piece of data has a precise and fixed location within a line in a data file. Moreover, the line length of CTfilcs is restricted to 80 characters. 

The scientific method, as mentioned, involves observation and experimentation (research) to discover or establish facts. These are followed by deduction or hypothesis, establishing theories or principles. This sequence, however, may be reversed. The noted twentieth-century philosopher Karl Popper, who also dealt with science, expressed the view that the scientist s work starts not with collection of data (observation) but with selection of a suitable problem (theory). In fact, both of these paths can be involved. vSignificant and sometimes accidental observations can be made without any preconceived idea of a problem or theory and vice versa. The scientist, however, must have a well-prepared, open mind to be able to recognize the significance of such observations and must be able to follow them through. Science always demands rigorous standards of procedure, reproducibility, and open discussion that set reason over irrational belief. 

In attempting to reach decisions, it is useful to make assumptions or guesses about the populations involved. Such assumptions, which may or may not be true, are called statistical hypotheses and in general are statements about the probability distributions of the populations. A common procedure is to set up a null hypothesis, denoted by which states that there is no significant difference between two sets of data or that a variable exerts no significant effect. Any hypothesis which differs from a null hypothesis is called an alternative hypothesis, denoted by Tfj. 

The larger variance is placed in the numerator. For example, the F test allows judgment regarding the existence of a significant difference in the precision between two sets of data or between two analysts. The hypothesis assumed is that both variances are indeed alike and a measure of the same a. 

The probabilistic nature of a confidence interval provides an opportunity to ask and answer questions comparing a sample s mean or variance to either the accepted values for its population or similar values obtained for other samples. For example, confidence intervals can be used to answer questions such as Does a newly developed method for the analysis of cholesterol in blood give results that are significantly different from those obtained when using a standard method or Is there a significant variation in the chemical composition of rainwater collected at different sites downwind from a coalburning utility plant In this section we introduce a general approach to the statistical analysis of data. Specific statistical methods of analysis are covered in Section 4F. 

In a study involving paired data the difference, d[, between the paired values for each sample is calculated. The average difference, d, and standard deviation of the differences, are then calculated. The null hypothesis is that d is 0, and that there is no difference in the results for the two data sets. The alternative hypothesis is that the results for the two sets of data are significantly different, and, therefore, d is not equal to 0. 

A statistical analysis allows us to determine whether our results are significantly different from known values, or from values obtained by other analysts, by other methods of analysis, or for other samples. A f-test is used to compare mean values, and an F-test to compare precisions. Comparisons between two sets of data require an initial evaluation of whether the data... 

Fisher s least significant difference a modified form of the f-test for comparing several sets of data. (p. 696) flame ionization detector a nearly universal GC detector in which the solutes are combusted in an H2/air flame, producing a measurable current, (p. 570)... 

Pulses of ions can be directed into the TOF analyzer at the rate of about 30 kHz, and, therefore, more than 30,000 spectra per second can be collected and summed. There are significant improvements in signal-to-noise ratios and speed of acquisition of data. 

Preprocessor. A device in a data-acquisition system that performs a significant amount of data reduction by extracting specific information from raw signal representations in advance of the main processing operation. A preprocessor can constitute the whole of a data-acquisition interface, in which case it must also perform the data-acquisition task (conversion of spectrometer signal to computer representation), or it can specialize solely in data treatment. 

What power dependence on M does r display according to these results Comment on the significance of the 3.4-power law according to these data and the results of the last problem. 

Beilstein Handbook of Organic Chemistry. This reference (55) is one of the most significant collections of data in organic chemistry. The physical and chemical properties of organic compounds are tabulated in more than 500 fields. Most of these fields are searchable, and a sample of the record for chlorobenzene [108-90-7] is shown in Table 3. 

The mechanism of action of nootropic agents has been proposed to be their abiUty to faciUtate information acquisition, consoHdation, and retrieval (36). No one particular effect has been observed with any consistency for these agents, thus whereas a considerable amount of diverse preclinical pharmacological behavioral data has been generated using these compounds, the significance of these results in predicting clinical efficacy has not been established (43,44). Reviews on the biochemical and behavioral effects of nootropics are available (45—47). 

Because each country has its own patent laws, the precise meaning of the bibhographic data and the legal significance of the pubUshed patent document vary from country to country. The Patent Cooperation Treaty (PCT) provides a recommended code to distinguish the various types of documents and to simplify storage and retrieval of patent data (2), but the code is implemented differentiy by different countries. For example, in the United States an A-document in 1995 was a patent in the Nethedands, an A-document was a pubUshed unexamined appHcation. It is essential to understand each country s system to interpret the status of its patent documents. 

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