Glossary

CDISC Analysis Data Model.

Any adverse change in health or side effect that occurs in a person who participates in a Clinical Research trial while the patient is receiving treatment or within a previously specified length of time after treatment completion.

Any variant form of a DNA sequence or marker at a particular locus.

A position that a researcher evaluates in an experiment. The alternative hypothesis, H1 (or Ha), is the hypothesis that sample observations are influenced by a specific non-random cause. It is rival to the Null Hypothesis, H0.

A computational task that uses input data and parameters in a statistical method or other algorithm to produce output in the form of files, data sets, tables, graphics, logs, and so on. Also known as an Analytical Process. Abbreviated as AP.

Statistical models and procedures that partition observed Variance in a Variable into components attributable to different variation sources. By analyzing comparisons of variance estimates, ANOVA can determine whether the Means of several groups are statistically equal.

In a Clinical Research trial, the group of patients receiving a certain type of therapy. For example, one arm of a clinical trial might consist of patients receiving a new medication, another arm might consist of a standard-of-care medication, and another a placebo pill.

A graphical representation of discrete or non-continuous data. It consists of rectangular bars whose lengths are proportional to the magnitude of the values that they represent. See Bar Chart.

Denotes Type II Error rate, and is related to the Power of a test power = 1-beta).

A Variable that contains two discrete values (0 and 1, for example).

A scientific field of study involving the integration and application of computer science, information technology, mathematics, and statistics to the fields of biology, genetics, genomics, and medicine.

A group of Organs that work together to perform a task. Examples in humans include the digestive system, the nervous system, and the endocrine system.

Used to display the response distribution at different combinations of factor levels. Box plots can reveal differences in the response Mean at different levels, suggesting Main Effects. Box plots can also reveal whether the response variation is homogenous across factor levels, an assumption made in ANOVA. See Box Plot.

All of the Observations with the same values for all BY Variables.

Clinical Data Interchange Standards Consortium, a nonprofit organization that has “established standards to support the acquisition, exchange, submission, and archive of Clinical Research data and Metadata” whose mission is “to develop and support global, platform-independent data standards that enable information system interoperability to improve medical research and related areas of health-care”. See the CDISC website for more information.

Direct representations of a data table, drawn as a rectangular array of cells with each cell corresponding to a data table entry. Colors are assigned to each cell based on the range and type of values found in the column

A Variable whose values can consist of alphabetic and special characters as well as numeric characters

An item in a dialog or that you can select without affecting any other items. You can deactivate a check box by selecting it again.

Bundled strands of DNA and Protein located in the Cell nucleus. Chromosomes are inherited from parents. Chromosome count per organism cell varies by species. Human cells contain 23 pairs of nuclear chromosomes.

A medical science branch focused on determining both the safety and effectiveness of diagnostic products, medications, medical devices, and treatment regimens for human health.

A statistical test used for repeated tests of nominal variable independence.

The probability of an event (for example, X) given that another specific event (for example, Y) occurs. Conditional probability is often expressed as P(X|Y) or PY(X).

A table used to record and analyze the relationship between two or more categorical variables. See Contingency Table.

Also known as the Pearson product-moment correlation coefficient, it is equal to the Covariance of two Variables divided by the product of their Standard Deviations.

An Independent Variable, not manipulated by the experimenter, that can influence the outcome of the experiment.

Comma-separated value format. This text format stores tabular data, with line breaks and commas used to delimit table rows and columns, respectively.

A tree-like diagram used to summarize a Clustering report. A dendrogram shows where each cluster divides in a hierarchical fashion. See Dendrogram.

A Residual that measures the disagreement between the maxima of the fitted and observed log likelihood functions.

A matrix of distances.

Deoxyribonucleic acid, a nucleic acid containing genetic instructions for the development and functioning of living organisms (except for RNA viruses). DNA segments encoding genetic information are known as Genes. Non-coding DNA can have structural or regulatory purposes.

The Double FDR method of Mehrotra and Heyse (2004)2Mehrotra DV, Heyse JH. (2004) Use of the false discovery rate for evaluating clinical safety data. Statistical Methods in Medical Research 13:227-238. is used to compare the incidence of adverse events among treatments, leveraging the grouping of related adverse events (typically defined by the MedDRA system organ class). The method considers whether related terms within a group show differences between the treatments and upweights or downweights the significance of an individual term within the group accordingly. In the 2004 paper, the FDR adjustment is performed twice, and simulations are used to control the false discovery rate. Mehrotra and Adewale (2011) refine the Double FDR method to avoid the need for simulations by applying FDR adjustment thrice.

A scalar value that determines by how much a corresponding eigenvector is scaled by the square matrix for which it is defined. In principal components analysis, the eigenvalues of the Covariance or Correlation matrix represent the Variance of the components.

A record or display of a person’s heartbeat produced by electrocardiography, the transthoracic interpretation of electrical activity of the heart over a period of time.

The distance between two points that would be measured with a ruler. It is derived from the Pythagorean equation: a2 + b2 = c2.

Also referred to as an Independent Variable or predictor variable, a factor is a Variable included in a model to account for variation in a response. Factors are the variables whose values (levels) you set to study their relationship to a response. You often experiment with many potentially influential factors at the same time.

The probability of making one or more false discoveries (Type I Errors) among all hypotheses while performing multiple pairwise tests.

A statistical significance test used in the analysis of contingency tables where sample sizes are small. It is useful when you want to conduct a Chi-square Test, but one of your cells has an expected frequency of five or less. Its name is derived from its inventor, R.A. Fisher, and reflects that the significance of the deviation from a Null Hypothesis can be calculated exactly (as opposed to relying on an approximation whose exactness is realized only as sample size approaches infinity).

A graphical display designed to illustrate the relative strength of treatment effects (or relative degree of gene enrichment), in multiple quantitative scientific studies (or databases) addressing the same question. Forest plots generally display results for each study (or other data source) as horizontal lines representing the 95% confidence interval of the effect observed in that trial. See Forest Plot.

Molecular unit of heredity in a living organism, comprising a contiguous sequence of DNA or RNA, coding for a Protein or RNA chain, which in turn has a function in the organism.

A Variable that is used for grouping results.

Chemical-driven damage (toxicity) to the liver.

The second-highest level of the Medical Dictionary for Regulatory Activities (MedDRA) Hierarchy, below System Organ Class (SOC) and above High Level Term (HLT). An example of an HLGT is “Respiratory tract infections”.

A nonparametric measure of association that detects general departures from independence. This Statistic approximates a weighted sum over observations of chi-square statistics for two-by-two classification tables.

The most popular markup language used in web pages.

An ominous prognostic indicator (in Clinical Research) that a pure drug-induced liver injury (DILI) leading to jaundice, without a hepatic transplant, has a case fatality rate of 10-50%.

This Variable does not depend on the value of another variable; it represents the condition or parameter that is manipulated by the investigator. In a two-dimensional plot, the independent variable is usually plotted on the x (horizontal) axis.

A random shifting of points by a slight amount along an axis so that more of those points can be effectively visualized in a graphical display.

In JMP, a journal is a file (.jrn) that contains results of user-specified reports.

A curve based on the survival function estimator from life-time or clinical outcome data. For example, it can be used to measure the proportion of patients living for a given amount of time after treatment, or to measure the time until a tumor disappears.

A statistical method that creates optimally separated groups of Observations in data using one of several methods. A set of points called cluster seeds is selected as a first guess of the means of the clusters. One cluster seed is selected for each of k clusters. Each observation is assigned to the nearest seed to form temporary clusters. The seeds are then replaced by the Means of the temporary clusters, and the report is repeated until no further changes occur in the clusters.

In a Tree Map, a leaf is any segment that is not further segmented. The final leaves in a tree are called terminal nodes.

A nonparametric Hypothesis Test to compare the survival distributions of two samples. It is appropriate when data are right-skewed and non-informatively censored. Also known as a Mantel-Cox test. This test can be considered a time-stratified Cochran-Mantel-Haenszel Test.

A generalized linear model used for prediction of the probability of event occurrence (Binomial Regression) by fitting data to a Logit Function logistic curve.

See Logit Function.

Least squares Means, which are estimates of means of classification effects that would be observed, assuming that the experimental design is balanced.

A distance measure based on Correlations between Variables. In contrast to Euclidean Distance, it is better adapted to non-spherically symmetric distributions, and is scale-invariant. See Mahalanobis Distances.

Multivariate analysis of covariance; an extension of the analysis of covariance (ANCOVA) for multiple Dependent Variables or where it is not feasible to combine dependent variables. MANCOVA is similar to MANOVA, but enables control for additional continuous Independent Variables (Covariates).

Multivariate analysis of variance, a generalized form of univariate analysis of variance (ANOVA), used when there are two or more Dependent Variables. This analysis is useful in determining whether changes in the Independent Variables have significant effects on the dependent variables, as well as the associated interactions among dependent and independent variables.

Mathematical average for a collection of n Observations. It is calculated by dividing the sum of the observations by n.

In any set of n Observations arranged in order of magnitude, the median is represented by the observation positioned at n/2.

Descriptive data on the content of primary data.

A value in the SAS System indicating that no data is stored for the Variable in the current Observation. It is indicated by a single dot (.) for a numeric variable or a blank for a character variable.

The value that occurs most often in a probability Distribution or data set.

An argument of proof by contradiction; often known as denying the consequent. It has the general argument form of:

1. If P, then Q.

2. Not Q.

3. Therefore, not P.

A Variable that contains discrete values that do not have a logical order. Includes names and other verbal descriptions.

A Variable that contains only numeric values and related symbols, such as decimal points, plus signs, and minus signs.

Analysis of variance with one between-groups factor. This is useful when you have a nominal Independent Variable and a normally distributed interval Dependent Variable, and you want to compare differences in the means of the dependent variable according to levels of the independent variable.

Analysis of variance used on one nominal Independent Variable and a normally distributed interval Dependent Variable that is repeated at least twice for each subject. This method is equivalent to the paired samples t-test, but allows for two or more nominal variable levels.

The established systematic tendency for humans to be overly optimistic about the outcome of planned actions. The likelihood of positive and negative events are over- and under-estimated, respectively. This tendency varies based on person and type of action.

A collection of Tissues combined in one structure to serve a particular function.

A plot consisting of connected line segments across all responses for each row in a data table. See Parallel Plot.

A parametric measure of association for two variables. It measures both the strength and the direction of a linear relationship. If one variable X is an exact linear function of another variable Y, a positive relationship exists if the correlation is 1 and a negative relationship exists if the correlation is -1. If there is no linear predictability between the two variables, the correlation is 0. If the two variables are normal with a correlation 0, the two variables are independent. However, correlation does not imply causality because, in some cases, an underlying causal relationship might not exist.

The value of a Variable below which a certain percent of Observations fall. For example, the 60th percentile is the value below which 60% of the observations can be found. Note the following percentile landmarks.

- 25th percentile = first quartile = Q1

- 50th percentile = second quartile = median = Q2

- 75th percentile = third quartile = Q3

An open standard for document exchange, created by Adobe Systems, that is used for representation of documents in a software, hardware, and operating system-independent manner.

The probability of a statistical significance test enabling you to reject the Null Hypothesis when the Alternative Hypothesis is true. Power equals one minus Beta (the rate of Type II Error).

The probability of an event computed before collection of new data (often based on an experienced expert opinion or rules-of-thumb). An experimenter begins with a prior probability of an event and then revises it in light of new data. Contrast with posterior probability.

A biochemical compound consisting of polypeptides, ordered as folded chains, sheets, or more complex three-dimensional structures. Proteins can have structural or functional roles in organisms.

The list of menu items or choices that appears when you choose an item from a Menu Bar or from another menu.

The n x p population structure incidence matrix where n is the number of individuals assayed and p is the number of populations defined.

The effects that cause extraneous variation in your results and have little to do with the questions being addressed. Random effects include factors such as physical differences between the arrays, or batch effects resulting from performing different parts of the experiments at different times, on different days, using different lots of reagents, and so on. Variation resulting from random effects can confound your results and should be eliminated from your analysis.

Techniques for modeling and analyzing several Variables, with the focus on the relationship between dependent and independent variables. Regression analysis is useful in uncovering how values of a Dependent Variable change when a single Independent Variable is varied.

Value equal to the response value minus the predicted value.

A proprietary document file format created by Microsoft, used in many word processing programs.

Reporting Odds Ratio5Meyboom RHB, Egberts ACG, Edwards IR, Hekster YA, de Koning FHP, Gribnau FWJ. (1997) Principles of signal detection in pharmacovigilance. Drug Safe 16: 355–365.

A file whose contents are in one of the native SAS file formats. SAS data sets contain data values in addition to descriptor information that is associated with the data.

Variables (columns) in a SAS data set can have a SAS Variable Label. This label has much less restrictive creation rules than the corresponding SAS Variable Name. Blank spaces, special characters, and longer lengths are permitted.

A graph showing the relationship between two Variables. Multiple scatterplot formats exist, including scatterplot matrices, three-dimensional scatterplots, and Bubble Plots. See Reliability Diagram.

CDISC Study Data Tabulation Model. See (SDTM for more details.

A graphical display enabling you to compare how an experimental population responds to an experimental treatment. See Shift Plot.

A number determining the degree of smoothing for certain algorithms.

The proportion of true negatives that are correctly identified. Specifically, specificity equals the number of true negatives divided by the sum of the number of true negatives and the number of false positives.

The standard deviation of the sample mean. It is calculated by dividing the Standard Deviation by the square root of the Sample Size.

Multiple meanings are possible:

- Transformation of a data set to have zero Mean and unit Variance.

- Making all regression coefficients have the same scale.

- Normalization.

A Variable that partitions the data into blocks with similar characteristics.

Plots of survival functions estimated for each subject. See Survival Curves.

The highest level of the Medical Dictionary for Regulatory Activities (MedDRA) Hierarchy, above High Level Group Term (HLGT). An example of an SOC is “Respiratory, thoracic, and mediastinal disorders”.

A nonparametric measure of association based on the number of concordances and discordances in paired Observations. Concordance occurs when paired observations vary together, and discordance occurs when paired observations vary differently. Also, used for the truncated product p-Value adjustment method to indicate that there is at least one false Null Hypothesis among those with p-values less than tau when the null hypothesis is rejected.

A collection of Cells from the same origin that achieves a specific function. The cells do not need to be identical in morphology or genomic content, but must have identical function. Examples of animal and plant tissues include muscle and meristematic tissues, respectively.

The complete set of rules that are used to split data into a hierarchy of successive segments. A tree consists of branches and leaves, in which each set of leaves represents an optimal segmentation of the branches above them according to a statistical measure.

A method that smooths p-Values over s of markers for n Hypothesis Tests by taking the product of those p-values less than a specified cutoff value and evaluating the probability of this product under the overall hypothesis that all n hypotheses are true.

A test that assesses the statistical difference between the Means of two different experimental groups. The Test Statistic follows a Student’s t distribution if the Null Hypothesis is supported.

If only one Variable is chosen (one-sample t-test), the null hypothesis is that “the population mean is equal to the given mean”.

An incorrect decision made when a test fails to reject a false Null Hypothesis (H0). This is comparable to a false negative error. Type II error rate is denoted by Beta, and is related to the Power of a test (power = 1-beta).

A measure of deviation of a group of samples from the mean. It is calculated by squaring the Standard Deviation.

Measures of physiological statistics used to assess basic body functions. The most common vital signs include body temperature, heart rate (or pulse), blood pressure, and respiratory rate.

A SAS statement that enables you to filter a set of Observations so that only the subset of data meeting the specific filtering criteria are considered in the analysis.

A nonparametric statistical hypothesis test used when comparing two related samples or repeated measurements on a single sample to assess whether their population Mean ranks differ. It is appropriate as an alternative to the paired Student’s t-test when the population is not normally distributed or the data is ordinal.

A series of processes run in a specified order, whose output is collected in a Journal. Given a constant basic experimental design and analysis objectives, a workflow can be used repeatedly with different data sets.