Medical Terminology: Research

Statistical procedures for analysis of data that contain a continuous dependent variable and more than one nominal independent variable. ANOVA procedures include one-way and factorial ANOVA.

A condition that produced results which depart from the true values in a consistent direction. (syn: systematic error)

A study that begins by identifying individuals with a disease (cases) and individuals with a disease (controls). The cases and controls are identified without knowledge of an individuals's exposure or non exposure to factors being investigated. These factors are determined from existing information (syn: retrospective).

A standard mathematical distribution that can be sued to calculate the P values and confidence intervals in a variety of statistical procedures for nominal dependent variables.

A group of persons used for comparison with a study group. Ideally, the control group is identical to the study group except that it does not possess the characteristic or has not been exposed to the treatment under study (syn: reference group).

A statistic used for studying the strength of an association between two variables, each of which has been sampled using a representative or naturalistic method from a population of interest.

An estimate of the strength of the association between a dependent variable and an independent variable when both are obtained using naturalistic sampling.

A type of paired design in which the same individual receives a study and a control therapy and an outcome is assessed for each therapy.

Generally, the outcome variable of interest in any type of research study. The outcome that one intends to explain or estimate.

Frequencies or relative frequencies of all possible values of a characteristic. Population and sample distribution can be described graphically or mathematically. One of the purposes of statics is to estimate parameters of population distributions.

The extent to which a treatment produces a beneficial effect when assessed under the ideal conditions of an investigation. Efficacy is to therapy what contributory cause is to etiology of disease.

Conclusions drawn about the meaning of the study for a target population that includes types of individuals or data not represented in the study sample.

An individual whose result on a test is negative but who has the disease or condition as determined by the gold standard.

An individual whose result on a test is positive but who does not have the disease or condition as determined by the gold standard.

A distribution of data assumed in many statistical procedures.The Gaussian distribution is a symmetrical, continuous, bell-shaped curve with its mean value corresponding to the highest point on the curve (syn: normal distribution).

The rate at which new cases of disease occur per unit of time. the incidence rate is theoretically calculated as the number of individuals who develop the disease over a period of time divided by the total person-years of observation (syn: hazard).

Variable(s) being measured to determine the corresponding measurement of the dependent variable in any type of research study. Independent variables define the conditions under which the dependent variable is to be examined.

A method for data analysis in a randomized clinical trial in which individual outcomes are analyzed according to the group to which they have been randomized even if they never received the treatment which they were assigned.

Interaction occurs when the relationship between variables is altered by the value of another variable (syn: synergy).

A series of methods for systematically combing information from more than one investigation in order to draw a conclusion which could not be drawn solely on the basis of the single investigations.

The assertion that no true association of difference between variables exists in the larger population from which the study samples are obtained.

The proportion of those with a positive test who actually have the condition or disease as measured by the Gold Standard. This measure incorporates the prevalence of the condition or disease. Clinically, the predictive value of a positive test is the probability that an individual has the disease if the test is positive.

Used to refer to the outcome measurement in a study which is used to calculate the sample's size. It should be a frequently occurring and biologically important end point. (Secondary End Point - An end point which is of interest and importance, such as death, but which occurs too infrequently to use to calculate the sample's size.)

The degree to which a test gives the same result when the same entity is measured twice (or more).

A characteristic or factor that has been shown to be associated with an increased probability of developing a condition or disease. A risk factor does not necessarily imply a cause and effect relationship. A risk factor implies that at least an association has been established on an individual level.

Preinvestigation observation of patients usually designed to ensure that they are appropriate candidate for entrance into a randomized clinical trail, especially with regard to their adherence to therapy.

A subset of a larger population obtained for investigation to draw conclusions or make estimates about the larger population.

An error introduced by chance differences between the estimate obtained in a sample and the true value in the larger population from which the sample was drawn. Sampling error is inherent in the use of sampling methods and is measured by the standard error.

The principles and procedures used tin the systematic pursuit of knowledge. It involves the recognition and formulation of a problem, the collection of data through observation or experiment, the formulation of a hypothesis and the testing and confirmation of the hypothesis.

A bias in assignment that occurs when the study and control groups are chosen so that they differ from each other by one r more factors that affect the outcome of the study. A special type of confounding variable that results from study design rather than chance.

A statistical technique for determining the probability that the data observed in a sample or more extreme data could occur by chance if there is no such difference or association in the larger population (syn: inference, hypothesis testing).

An assertion that an association or difference exists between two or more variables in the population sampled. A study hypothesis can be one-tailed, considering associations or differences in one direction only, or two-tailed, not specifying the direction of the association or difference.

A test is valid if it is appropriate for the question being asked and is accurate and precise.