Once data is collected from both the experimental and the control groups, a statistical analysis is conducted to find out if there are meaningful differences between the two groups. A statistical analysis determines how likely any difference found is due to chance and thus not meaningful. For example, if an experiment is done on the effectiveness of a nutritional supplement, and those taking a placebo pill and not the supplement have the same result as those taking the supplement, then the experiment has shown that the nutritional supplement is not effective. Generally, psychologists consider differences to be statistically significant if there is less than a five percent chance of observing them if the groups did not actually differ from one another. The greatest strength of experiments is the ability to assert that any significant differences in the findings are caused by the independent variable. This occurs because random selection, random assignment, and a design that limits the effects of both experimenter bias and participant expectancy should create groups that are similar in composition and treatment.
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Instrument is the general term that researchers use for a measurement device survey, test, questionnaire, etc. To help distinguish between instrument and instrumentation, consider that the instrument is the device and instrumentation is the course of action the process of developing, testing, and using the device. Instruments fall into two broad categories, researcher-completed and subject-completed, distinguished by those instruments that researchers administer versus those that are completed by participants. Researchers chose which type of instrument, or instruments, to use based on the research question. Examples are listed below:. Example usability problems include:. Validity and reliability concerns discussed below will help alleviate usability issues.
Ultrasound is outstripping other diagnostic imaging techniques in the evaluation of osteoarthritis OA. Due to its sub-millimetric resolution, ultrasound has the ability to detect minimal morphostructural abnormalities, even from preclinical or asymptomatic disease stages located in the main joint structures predominantly affected by OA: articular cartilage, synovial membrane, and subchondral bone. As of today, ultrasound has proven to be a useful tool for the detection of abnormalities occurring within soft tissues, including synovial hypertrophy, fluid accumulation, and synovial cysts, as well as bony abnormalities, such as osteophyte formation.
Metrics details. There are a number of instruments that describe severity and progression of multiple sclerosis and they are increasingly used as endpoints to assess the effectiveness of therapeutic interventions. We examined to what extent the psychometric properties of two accepted instruments — EDSS and MSFC — meet methodological standards and the value they have in clinical trials.