Glosario de IVD y diagnóstico molecular

The quality of nearness to the truth or the true value.

The goodness of fit statistic for the terminal elimination phase, adjusted for the number of time points used in the estimation of Lambda z.

A statistical technique which helps in making inference whether three or more samples might come from populations having the same mean; specifically, whether the differences among the samples might be caused by chance variation.

The area between the x-axis and the curve given by the integrand. It is equal to the definite integral of a function. In the field of pharmacokinetics, the area under the curve (AUC) is the area under the curve in a plot of concentration of a drug in plasma against time. AUC is usually given for the time interval zero to infinity, and other time intervals are indicated.

The sum of a set of values divided by the number of values in the set.

A methodical examination or review of a condition or situation.

Existing conditions, especially those that would be confused with the phenomenon to be observed or measured.

A starting point to which things may be compared.

A sequential p-value procedure that controls expected false discovery rate.

Any deviation of results or inferences from the truth, or processes leading to such deviation.

A family of discrete probability density functions, which models systems that meet the following requirements: 1) the number of trials (n) is fixed; 2) there are only two outcomes for each trial, success or failure; 3) the outcome of each trial is independent; and 4) all trials have the same probability (p) of success. Binomial distributions show the likelihood of the number of successful trials versus the total number of trials.

A biological or chemical substance that exerts toxic or pathologic effects on living entities.

A characteristic of experiment design in which one or more groups involved (receiving, administering, or evaluating intervention) are unaware of which intervention any particular subject is receiving.

The act of checking or adjusting (by comparison with a standard) the accuracy of a measuring instrument.

An instrument designed to measure the size of an opening or one used to increase the diameter of an opening; can also refer to a standard or reference material used to set the operating parameters of an instrument.

A study that compares two groups of people: those with the disease or condition under study (cases) and a very similar group of people who do not have the disease or condition (controls). Researchers study the medical and lifestyle histories of the people in each group to learn what factors may be associated with the disease or condition. For example, one group may have been exposed to a particular substance that the other was not. Also called retrospective study.

The process by which a person demonstrates specific knowledge, skills, or abilities in the view of a certifying body. Similarly, the process by which a product or process can achieve certification indicating its suitability for a specific purpose.

Chi-square test is a statistical test for testing the null hypothesis that the distribution of a discrete random variable coincides with a given distribution. It is one of the most popular goodness-of-fit tests.

The ratio of standard deviation to mean, expressed as a percentage or fraction.

A research study that compares a particular outcome (such as lung cancer) in groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke compared with those who do not smoke).

A range of values for a parameter that may contain the parameter and the degree of confidence that it is in fact there.

The presence of any substance or organism that makes a preparation impure.

The degree to which two or more quantities or events are linearly associated, a statistical relation between two or more variables such that systematic changes in the value of one variable are accompanied by systematic changes in the others.

Problem associated with the degree to which an antibody or antigen participates in cross reactions.

A study in which participants are examined once for a characteristic, such as disease, at a single point in time.

A statistical method of partitioning a sample of data into subsets such that the analysis is initially performed on a single subset, while the other subsets are retained for subsequent use in confirming and validating the initial analysis.

The proportion of all the observations that have been classified correctly by the diagnostic procedures in given population, or using some diagnostic test, or by some medical institution or professional.

The probability that a test will produce a true negative result when used on non-effected subjects as compared to a reference or "gold standard". The specificity of a test can be determined by calculating: number of true negative results divided by the sum of true negative results plus number of false positive results.

The largest difference between, or ratio of, an instrument's or method's highest and lowest value in a set, such as pixel (voxel) values in an image.

A statistical method used for multiple testing corrections to control the expected proportion of false positives (Type I error) among rejected tests or hypotheses. It is less stringent than other multiple testing corrections and thereby, will allow a percentage of false positives.

A test result that shows no evidence of a result or condition although it is present.

Problem associated with the device incorrectly reporting that something has not been detected and may mislead the operator into not taking certain actions when action should be taken.

A test result that shows evidence of a result or condition although it is not actually present.

Problem associated with the device incorrectly reporting that something has been detected and may mislead the operator to take certain actions.

The n-th root of the multiple products of n values, as contrasted with the normally understood arithmetic mean.

Disruption of the integrity of the erythrocyte membrane causing release of hemoglobin.

The relative frequency of occurrence of something.

Validation evidence that an assay detects the range of variants, genotypes, or serotypes it claims to cover. For evolving targets such as influenza or SARS-CoV-2, inclusivity statements carry a validation date and should be checked against circulating variant lists at procurement time.

The act of hindering or obstructing or impeding.

The difference between the 3rd and 1st quartiles is called the interquartile range and it is used as a measure of variability (dispersion).

A nonparametric test for finding if three or more independent samples come from populations having the same distribution. It is a nonparametric version of ANOVA.

The lowest concentration of an analyte that can be quantified with acceptable accuracy and precision under stated conditions — distinct from, and higher than, the limit of detection.

The formula to calculate body surface area as described by John D. Current. It is mathematically defined as: BSA (m^2) = 1321 + 0.3433 x Weight(g)

The value which has an equal number of values greater and less than it.

Required or expected data that is not present, which may be due to non-completion or corruption.

A test result that indicates that a specific disease, condition, or attribute being assessed is not present.

Any part of a signal that is not the true or original signal but is introduced by the communication mechanism.

In statistical inference procedures (hypothesis tests and confidence intervals), nonparametric procedures are those that are relatively free of assumptions about population parameters.

A family of probability density functions whose mean, median and mode are identical. The function generates a symmetrical curve, whose position and shape is determined by its location and scale parameters, the mean and standard deviation respectively. The standard normal distribution has a location parameter of 0 and a scale parameter of 1.

A statistical method to test if observations are significant or due to chance. It proposes that no statistical significance exists in a set of given observations and attempts to show that no variation exists between variables or that a single variable is no different than its mean. It is presumed to be true until statistical evidence nullifies it for an alternative hypothesis.

The ratio of the odds of an event occurring in one group to the odds of it occurring in another group, or to a sample-based estimate of that ratio.

An observation in a data set that is numerically distant from the rest of the data.

A method used to test whether the mean difference between pairs of measurements in a related group are significant.

In statistical inference procedures (hypothesis tests and confidence intervals), parametric procedures are those that incorporate assumptions about population parameters.

How close amplification is to ideal doubling each cycle, reported as a percentage or derived from the standard curve slope. Efficiency near 90–110% with a linear standard curve supports quantification claims; it is a standard checklist item when auditing assay validation dossiers.

A measure of the correlation of two variables X and Y measured on the same object or organism, that is, a measure of the tendency of the variables to increase or decrease together. It is defined as the sum of the products of the standard scores of the two measures divided by the degrees of freedom.

Any of the 99 numbered points that divide an ordered set of scores into 100 parts each of which contains one-hundredth of the total.

A distribution function used to describe the occurrence of rare events or to describe the sampling distribution of isolated counts in a continuum of time or space. This special probability distribution can apply to the number of discrete independent random events occurring in a given interval when knowing their average rate of occurrence over a very long interval.

A quantitative representation of the degree of accuracy necessary for or associated with a particular action.

An expression of the likelihood that a given test result correlates with the presence or absence of disease.

The ratio (for a given time period) of the number of occurrences of a disease or event to the number of units at risk in the population.

A program for the determination of laboratory performance where individual labs perform the same test on the same or similar items or materials, with the results from each lab compared and evaluated.

A type of study in which participants are enrolled into the study before they develop the disease or outcome in question.

A measure of the probability that a result happened by chance. The lower the p-value, the more likely it is that the result was caused by phenomenon of interest.

Programs of regular assessment of medical and nursing activities to evaluate the quality of medical care including all actions taken to ensure that standards and procedures are adhered to and that delivered products or services meet performance requirements.

Set of measurements and inspections taken to verify that performance of equipment and procedures remains within specified limits.

Any of four equal-sized sets of observations in a ranked sample.

The minimum False Discovery Rate (FDR) value required for a test to be considered significant.

A study in which the participants are assigned by chance to separate groups to evaluate treatments. The study also includes a control group, which is undergoing the same rigors of the study with placebo treatment or standard treatment. The trial can also be controlled by the addition of a test group to ensure there are no factors present to skew the results and by the inclusion of peer-review analysis by appropriate government officials. 2005

The difference between the lowest and highest numerical values; the limits or scale of variation.

A set of values of particular type of measurement that is used to interpret corresponding observation results.

Complementary precision measures: repeatability is variation under the same conditions (same operator, equipment, short interval); reproducibility is variation across conditions — different days, operators, lots, or laboratories.

The ability to yield similar results given a set of constraints.

A study in which participants with known outcomes are assessed based on data collected before the study.

The goodness of fit statistic for the terminal elimination phase.

Impregnation of one substance by another to the greatest possible extent; that concentration of a dissolved substance that cannot be exceeded.

Bias encountered due to enrolling study participants that do not reflect the intended target population.

The ability to respond to physical stimuli or to register small physical amounts or differences.

A detectable physical quantity or impulse (e.g., voltage, current, or magnetic field strength).

The ratio of a measure of useful information from a system to that of a measure of interfering unwanted, often random, information that is also present.

A measure of the range of values in a set of numbers. Standard deviation is a statistic used as a measure of the dispersion or variation in a distribution, equal to the square root of the arithmetic mean of the squares of the deviations from the arithmetic mean.

The standard deviations of the sample in a frequency distribution, obtained by dividing the standard deviation by the square root of the total number of cases in the frequency distribution.

An established procedure to be followed in carrying out a given operation or in a given situation.

The substitution of some value for a missing data point or a missing component of a data point.

A measure of the likelihood that a significance test will detect an effect or difference in a sample if the effect or difference exists in the entire population from which that sample was taken.

A test used to determine the statistical significance of an observation.

The lowest limit at which something becomes detectable or relevant.

A method for converting an individual score into a standard form. While similar to a z-score, t-score is used when the conversion is made without knowledge of the population standard deviation and mean.

A statistical hypothesis test that controls directional errors if rejection of a hypothesis is the result of a directional decision. The two-sided test has less statistical power than the one-sided test.

A measure of the variability in a sample or population. It is calculated as the mean squared deviation (MSD) of the individual values from their common mean. In calculating the MSD, the divisor n is commonly used for a population variance and the divisor n-1 for a sample variance.

A method for converting an individual score into a standard form. The z-score indicates how far and in what direction an item deviates from its distribution's mean, expressed in units of standard deviation. Calculation of a z-score requires knowledge about the population's standard deviation and mean.