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Scientific Control
A scientific control is an experiment or observation designed to minimize the effects of variables other than the independent variable (i.e. confounding variables). This increases the reliability of the results, often through a comparison between control measurements and the other measurements. Scientific controls are a part of the scientific method. Controlled experiments Controls eliminate alternate explanations of experimental results, especially experimental errors and experimenter bias. Many controls are specific to the type of experiment being performed, as in the molecular markers used in SDS-PAGE experiments, and may simply have the purpose of ensuring that the equipment is working properly. The selection and use of proper controls to ensure that experimental results are valid (for example, absence of confounding variables) can be very difficult. Control measurements may also be used for other purposes: for example, a measurement of a microphone's background noise in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Starr 011107-0010 Argyroxiphium Sandwicense Subsp
Starr may refer to: People and fictional characters * Starr (surname), a list of people and fictional characters * Starr (given name), a list of people and fictional characters Places United States * Starr, Ohio, an unincorporated community * Starr, South Carolina, a town * Starr County, Texas * Starr Township, Cloud County, Kansas * Starr Township, Hocking County, Ohio * Starr Historic District, Richmond, Indiana * Mount Starr, a mountain in California Antarctica * Starr Peninsula, Ellsworth Land * Starr Lake (McMurdo Station), Ross Island * Starr Nunatak, Victoria Land Elsewhere * Starr Gate, a location in Blackpool, Lancashire, England * 4150 Starr, a minor planet Buildings * Starr House (other), various houses on the United States National Register of Historic Places * Starr Mill, Middletown, Connecticut, on the National Register of Historic Places * Starr Arena, a sports facility in Hamilton, New York, United States Ships * HMS ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NCO Figure
NCO may refer to: * NCO Group, an international corporation * National Children's Orchestra of Great Britain * Net capital outflow, an economic metric * NetCDF Operators, software * Network-centric operations, a theory of war in the information age * Non-commissioned officer A non-commissioned officer (NCO) is an enlisted rank, enlisted leader, petty officer, or in some cases warrant officer, who does not hold a Commission (document), commission. Non-commissioned officers usually earn their position of authority b ..., a category of military rank * Numerically controlled oscillator, a digital signal generator * Nuova Camorra Organizzata, a defunct Italian criminal organization * Isocyanate, a functional group of atoms –N=C=O * Quonset State Airport, airport with this IATA code * Indian National Congress (Organisation), a former Political Party in India formally referred as NCO by the Election Commission of India. * Nevada–California–Oregon Railway, a defu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sham Surgery
Sham surgery (or placebo surgery) is a faked surgical intervention that omits the step thought to be therapeutically necessary. In clinical trials of surgical interventions, sham surgery is an important scientific control. This is because it isolates the specific effects of the treatment as opposed to the incidental effects caused by anesthesia, the incisional trauma, pre- and postoperative care, and the patient's perception of having had a regular operation. Thus sham surgery serves an analogous purpose to placebo drugs, neutralizing biases such as the placebo effect. Human research A number of studies done under Institutional Review Board-approved settings have delivered important and surprising results. With the progress in minimally invasive surgery, sham procedures can be more easily performed as the sham incision can be kept small similarly to the incision in the studied procedure. A review of studies with sham surgery found 53 such studies: in 39 there was improvement w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Confirmation Bias
Confirmation bias (also confirmatory bias, myside bias, or congeniality bias) is the tendency to search for, interpret, favor and recall information in a way that confirms or supports one's prior beliefs or Value (ethics and social sciences), values. People display this bias when they select information that supports their views, ignoring contrary information or when they interpret ambiguous evidence as supporting their existing attitudes. The effect is strongest for desired outcomes, for emotionally charged issues and for deeply entrenched beliefs. Biased search for information, biased interpretation of this information and biased memory recall, have been invoked to explain four specific effects: # ''attitude polarization'' (when a disagreement becomes more extreme even though the different parties are exposed to the same evidence) # ''belief perseverance'' (when beliefs persist after the evidence for them is shown to be false) # the ''irrational primacy effect'' (a greater relia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Observer-expectancy Effect
The observer-expectancy effect is a form of reactivity in which a researcher's cognitive bias causes them to subconsciously influence the participants of an experiment. Confirmation bias can lead to the experimenter interpreting results incorrectly because of the tendency to look for information that conforms to their hypothesis, and overlook information that argues against it. It is a significant threat to a study's internal validity, and is therefore typically controlled using a double-blind experimental design. It may include conscious or unconscious influences on subject behavior including creation of demand characteristics that influence subjects, and altered or selective recording of experimental results themselves. Overview The experimenter may introduce cognitive bias into a study in several in the observer-expectancy effect, the experimenter may subtly communicate their expectations for the outcome of the study to the participants, causing them to alter their be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Placebo
A placebo ( ) can be roughly defined as a sham medical treatment. Common placebos include inert tablets (like sugar pills), inert injections (like saline), sham surgery, and other procedures. Placebos are used in randomized clinical trials to test the efficacy of medical treatments. In a placebo-controlled trial, any change in the control group is known as the ''placebo response'', and the difference between this and the result of no treatment is the ''placebo effect''. Placebos in clinical trials should ideally be indistinguishable from so-called verum treatments under investigation, except for the latter's particular hypothesized medicinal effect. This is to shield test participants (with their consent) from knowing who is getting the placebo and who is getting the treatment under test, as patients' and clinicians' expectations of efficacy can influence results. The idea of a placebo effect was discussed in 18th century psychology, but became more prominent in the 20th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bias
Bias is a disproportionate weight ''in favor of'' or ''against'' an idea or thing, usually in a way that is inaccurate, closed-minded, prejudicial, or unfair. Biases can be innate or learned. People may develop biases for or against an individual, a group, or a belief. In science and engineering, a bias is a systematic error. Statistical bias results from an unfair sampling of a population, or from an estimation process that does not give accurate results on average. Etymology The word appears to derive from Old Provençal into Old French ''biais'', "sideways, askance, against the grain". Whence comes French ''biais'', "a slant, a slope, an oblique". It seems to have entered English via the game of bowls">English (language)">English via the game of bowls, where it referred to balls made with a greater weight on one side. Which expanded to the figurative use, "a one-sided tendency of the mind", and, at first especially in law, "undue propensity or prejudice". or ballast, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Soil Fertility
Soil fertility refers to the ability of soil to sustain agricultural plant growth, i.e. to provide plant habitat and result in sustained and consistent yields of high quality.Bodenfruchtbarkeit Retrieved on 2015-11-09. It also refers to the soil's ability to supply plant/crop nutrients in the right quantities and qualities over a sustained period of time. A fertile soil has the following properties: * The ability to supply essential plant nutrients and water in adequate amounts and proportions for plant growth and reproduction; and * The absence of toxic substances which may inhibit plant growth e. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crop Yield
In agriculture, the yield is a measurement of the amount of a crop grown, or product such as wool, meat or milk produced, per unit area of land. The seed ratio is another way of calculating yields. Innovations, such as the use of fertilizer, the creation of better farming tools, and new methods of farming and improved crop varieties have improved yields. The higher the yield and more intensive use of the farmland, the higher the productivity and profitability of a farm; this increases the well-being of farming families. Surplus crops beyond the needs of subsistence agriculture can be sold or bartered. The more grain or fodder a farmer can produce, the more draft animals such as horses and oxen could be supported and harnessed for labour and production of manure. Increased crop yields also means fewer hands are needed on farm, freeing them for industry and commerce. This, in turn, led to the formation and growth of cities, which then translated into an increased demand for foodst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Systematic Error
Observational error (or measurement error) is the difference between a measurement, measured value of a physical quantity, quantity and its unknown true value.Dodge, Y. (2003) ''The Oxford Dictionary of Statistical Terms'', OUP. Such errors are inherent in the measurement process; for example lengths measured with a ruler calibrated in whole centimeters will have a measurement error of several millimeters. The error or uncertainty of a measurement can be estimated, and is specified with the measurement as, for example, 32.3 ± 0.5 cm. Scientific observations are marred by two distinct types of errors, systematic errors on the one hand, and Statistical randomness, random, on the other hand. The effects of random errors can be mitigated by the repeated measurements. Constant or systematic errors on the contrary must be carefully avoided, because they arise from one or more causes which constantly act in the same way, and have the effect of always altering the result of the experi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Standard Curve
In analytical chemistry, a calibration curve, also known as a standard curve, is a general method for determining the concentration of a substance in an unknown sample by comparing the unknown to a set of standard samples of known concentration. A calibration curve is one approach to the problem of instrument calibration; other standard approaches may mix the standard into the unknown, giving an internal standard. The calibration curve is a plot of how the instrumental response, the so-called analytical signal, changes with the concentration of the analyte (the substance to be measured). General use In more general use, a calibration curve is a curve or table for a measuring instrument which measures some parameter indirectly, giving values for the desired quantity as a function of values of sensor output. For example, a calibration curve can be made for a particular pressure transducer to determine applied pressure from transducer output (a voltage). Such a curve is typicall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme Assay
Enzyme assays are laboratory methods for measuring enzymatic activity. They are vital for the study of enzyme kinetics and enzyme inhibition. Enzyme units The quantity or concentration of an enzyme can be expressed in molar amounts, as with any other chemical, or in terms of activity in enzyme units. Enzyme activity Enzyme activity is a measure of the quantity of active enzyme present and is thus dependent on various physical conditions, ''which should be specified''. It is calculated using the following formula: :\mathrm=\mathrm_\text=\mathrm\times\mathrm where :\mathrm = Enzyme activity :\mathrm_\text = Moles of substrate converted per unit time :\mathrm = Rate of the reaction :\mathrm = Reaction volume The SI unit is the katal, 1 katal = 1 mol s−1 (mole per second), but this is an excessively large unit. A more practical and commonly used value is enzyme unit (U) = 1 μmol min−1 (micromole per minute). 1 U corresponds to 16.67 nanokatals. Enzyme activity a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
