Uncontrolled experiments

Strength of recommendations A, B, C = good, moderate, and poor evidence to support recommendation, respectively. Quality of evidence 1 = Evidence from >1 properly randomized, controlled trial. 2 = Evidence from >1 well-designed clinical trial with randomization, from cohort or casecontrolled analytic studies from multiple time series, or from dramatic results from uncontrolled experiments 3 = Evidence from opinions of respected authorities, based on clinical experience, descriptive studies, or reports of expert communities... 

Level of evidence I, randomized controlled trials 11-1, controlled trials not randomized 11-2, cohort or case control studies 11-3, dramatic results from uncontrolled experiments III, expert opinion. 

II-3 Comparisons between times or places without intervention dramatic results in uncontrolled experiments... 

Controlled studies of IV verapamil have not been conducted in pediatric patients, but uncontrolled experience indicates that results of treatment are similar to those in adults. Patients less than 6 months of age may not respond to IV verapamil this resistance may be related to a developmental difference of AV node responsiveness. 

Antiemetics. Diphenidol (l,l-diphenyl- 4—piperidlnobutanol) has been reported to have antiemetic activity equal to chlorpromazine, but without many of the central neirvous system actions of the phenothia-zines. It blocked apomorphine induced emesis by oral, i.m., and rectal administration. In clinical trials dephenidol was found to be more effective than a placebo for relief of nausea and vomiting, with few side effectsxt was also found to be effective against various types of vomiting in man in an uncontrolled experiment. 

There have been two interruptions in the rise of global average temperature since 1956 (Fig. 3.5), and of course, the earth s climate is influenced by more than just CO2. Other trace gases and black carbon warm the climate, and aerosols cool it. On a larger scale, the astronomical theory of orbital influences was revived and climate variation attributed to such factors as ENSO, the Pacific Decadal Oscillation, and solar activities (or the lack thereof) are now being widely discussed. Still, more than 50 years later, scientists agree that the uncontrolled experiment pointed out by Plass in 1956 has been verified, and a warmer future caused by the radiative effects of CO2 is in store (Fleming 2010). 

Corrosion scientists work with two basic types of experiments, (1) controlled and (2) uncontrolled. In controlled experiments, levels of independent variables (factors such as temperature and chemical composition) are controlled and the dependent variables (corrosion rate, pitting potential, etc.) are measured. In uncontrolled experiments such as atmospheric exposures, uncontrolled independent variables such as temperature and relative humidity are measured along with the dependent corrosion results. Properly designed controlled experiments are much more amenable to statistical analysis of variance than are properly designed uncontrolled experiments. Many scientists prefer some form of factorial design for controlled experiments. 

A properly designed uncontrolled experiment is one that considers cJl the possible effects of uncontrolled variables. The corrosion researcher s knowledge of physical and chemical processes is most valuable in this respect. Changes in variables that are believed to cause effects along with the resulting effects should be measured. If an important variable is missed, all of the other data become less meaningful. 

For proper subsequent analysis, uncontrolled experiments require the collection of considerable data. For example, it is possible to collect ten sets of data involving nine uncontrolled variables and the measured corrosion results. The total is 100 bits of information that can be subjected to multiple regression analysis. If all of the variables are included in the analysis, a perfect mathematical fit can be obtained that is both physically and statistically meaningless. The experimental design does not consider the possibility of nonlinearity effects, interaction effects, nor error effects. One approach to eissure that enough data sets are collected is to count all of the physically and chemically (not mathematically) possible direct and interaction effects of the measured variables and multiply by 4 or 5 to account for possible nonlinearity and error. 

With the use of desktop computers and work stations now common, it is possible for corrosion researchers to put in their data and come out with analysis of variance tables for factorial experiments and multiple linetir regression analysis tables for uncontrolled experiments. Most such tables include a statistical test of significance for observed effects. That test (such as a F test) is a measure of the probability that an observed effect either exists or is caused by random error. 

Common sense is gained through uncontrolled experience scientific knowledge is gained through controlled experimentation. 

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