Scientific control in the context of Placebo-controlled

A natural experiment is a study in which individuals (or clusters of individuals) are exposed to the experimental and control conditions that are determined by nature or by other factors outside the control of the investigators. The process governing the exposures arguably resembles random assignment. Thus, natural experiments are observational studies and are not controlled in the traditional sense of a randomized experiment (an intervention study). Natural experiments are most useful when there has been a clearly defined exposure involving a well defined subpopulation (and the absence of exposure in a similar subpopulation) such that changes in outcomes may be plausibly attributed to the exposure. In this sense, the difference between a natural experiment and a non-experimental observational study is that the former includes a comparison of conditions that pave the way for causal inference, but the latter does not.

Natural experiments are employed as study designs when controlled experimentation is extremely difficult to implement or unethical, such as in several research areas addressed by epidemiology (like evaluating the health impact of varying degrees of exposure to ionizing radiation in people living near Hiroshima at the time of the atomic blast) and economics (like estimating the economic return on amount of schooling in US adults).

Telekinesis (from Ancient Greek τηλε- (tēle-) 'far off' and -κίνησις (-kínēsis) 'motion') (alternatively called psychokinesis) is a purported psychic ability allowing an individual to influence a physical system without physical interaction. Simply put, it is the moving or manipulating of objects with the mind, without directly touching them. Experiments to prove the existence of telekinesis have historically been criticized for lack of proper controls and repeatability. There is no reliable evidence that telekinesis is a real phenomenon, and the topic is generally regarded as pseudoscience.

Scientific evidence is evidence that serves to either support or counter a scientific theory or hypothesis, although scientists also use evidence in other ways, such as when applying theories to practical problems. Such evidence is expected to be empirical evidence and interpretable in accordance with the scientific method. Standards for scientific evidence vary according to the field of inquiry, but the strength of scientific evidence is generally based on the results of statistical analysis and the strength of scientific controls.

Physiological psychology is a subdivision of behavioral neuroscience (biological psychology) that studies the neural mechanisms of perception and behavior through direct manipulation of the brains of nonhuman animal subjects in controlled experiments. This field of psychology takes an empirical and practical approach when studying the brain and human behavior. Most scientists in this field believe that the mind is a phenomenon that stems from the nervous system. By studying and gaining knowledge about the mechanisms of the nervous system, physiological psychologists can uncover many truths about human behavior. Unlike other subdivisions within biological psychology, the main focus of psychological research is the development of theories that describe brain-behavior relationships.

Physiological psychology studies many topics relating to the body's response to a behavior or activity in an organism. It concerns the brain cells, structures, components, and chemical interactions that are involved in order to produce actions. Psychologists in this field usually focus their attention to topics such as sleep, emotion, ingestion, senses, reproductive behavior, learning/memory, communication, psychopharmacology, and neurological disorders. The basis for these studies all surround themselves around the notion of how the nervous system intertwines with other systems in the body to create a specific behavior.

Hard science and soft science are colloquial terms used to compare scientific fields on the basis of perceived methodological rigor, exactitude, and objectivity. In general, the formal sciences and natural sciences are considered hard science by their practitioners, whereas the social sciences and other sciences are described by them as soft science.

Precise definitions vary, but features often cited as characteristic of hard science include producing testable predictions, performing controlled experiments, relying on quantifiable data and mathematical models, a high degree of accuracy and objectivity, higher levels of consensus, faster progression of the field, greater explanatory success, cumulativeness, replicability, and generally applying a purer form of the scientific method. A closely related idea (originating in the nineteenth century with Auguste Comte) is that scientific disciplines can be arranged into a hierarchy of hard to soft on the basis of factors such as rigor, "development", and whether they are basic or applied.

Francesco Redi (18 February 1626 – 1 March 1697) was an Italian physician, naturalist, biologist, and poet. He is referred to as the "founder of experimental biology", and as the "father of modern parasitology". He was the first person to challenge the theory of spontaneous generation by demonstrating that maggots come from eggs of flies.

Having a doctoral degree in both medicine and philosophy from the University of Pisa at the age of 21, he worked in various cities of Italy. A rationalist of his time, he was a critic of verifiable myths, such as spontaneous generation. His most famous experiments are described in his magnum opus Esperienze intorno alla generazione degl'insetti (Experiments on the Generation of Insects), published in 1668. He disproved that vipers drink wine and could break glasses and that their venom was poisonous when ingested. He correctly observed that snake venoms were produced from the fangs, not the gallbladder, as was believed. He was also the first to recognize and correctly describe details of about 180 parasites, including Fasciola hepatica and Ascaris lumbricoides. He also distinguished earthworms from helminths (like tapeworms, flukes, and roundworms). He possibly originated the use of the control, the basis of experimental design in modern biology. A collection of his poems first published in 1685 Bacco in Toscana (Bacchus in Tuscany) is considered among the finest works of 17th-century Italian poetry, and for which the Grand Duke Cosimo III gave him a medal of honour.

Random assignment or random placement is an experimental technique for assigning human participants or animal subjects to different groups in an experiment (e.g., a treatment group versus a control group) using randomization, such as by a chance procedure (e.g., flipping a coin) or a random number generator. This ensures that each participant or subject has an equal chance of being placed in any group. Random assignment of participants helps to ensure that any differences between and within the groups are not systematic at the outset of the experiment. Thus, any differences between groups recorded at the end of the experiment can be more confidently attributed to the experimental procedures or treatment.

Random assignment, blinding, and controlling are key aspects of the design of experiments because they help ensure that the results are not spurious or deceptive via confounding. This is why randomized controlled trials are vital in clinical research, especially ones that can be double-blinded and placebo-controlled.

Remote viewing (RV) is the practice of seeking impressions about a distant or unseen subject, purportedly sensing with the mind. There is no scientific evidence that remote viewing exists, and the topic of remote viewing is generally regarded as pseudoscience. A remote viewer is expected to give information about an object, event, person, or location hidden from physical view and separated at some distance. Physicists Russell Targ and Harold Puthoff, parapsychology researchers at Stanford Research Institute (SRI), are generally credited with coining the term "remote viewing" to distinguish it from the closely related concept of clairvoyance. According to Targ, the term was first suggested by Ingo Swann in December 1971 during an experiment at the American Society for Psychical Research in New York City.

Remote viewing experiments have historically lacked proper controls and repeatability.

A placebo (/pləˈsiːboʊ/ plə-SEE-boh) 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.

Apoptotic DNA fragmentation is a key feature of apoptosis, a type of programmed cell death. Apoptosis is characterized by the activation of endogenous endonucleases, particularly the caspase-3 activated DNase (CAD), with subsequent cleavage of nuclear DNA into internucleosomal fragments of roughly 180 base pairs (bp) and multiples thereof (360, 540 etc.). The apoptotic DNA fragmentation is being used as a marker of apoptosis and for identification of apoptotic cells either via the DNA laddering assay, the TUNEL assay, or the by detection of cells with fractional DNA content ("sub G₁ cells") on DNA content frequency histograms e.g. as in the Nicoletti assay.