Table 1.
MPD Definitions
| Term | Definition | Relationships | Comments |
|---|---|---|---|
| MPD Project | Entity that logically binds a scientific investigation's unique dataset, protocols and other documentation necessary to evaluate and use the data. | An MPD project has only one primary dataset and one protocol. | A project usually represents the characterization of a cohort of animals tested for multiple traits; a project can stand alone in that the source (submitting investigator), all the data, and all the information needed to understand the data are bound. |
| MPD Protocol | Entity that binds one or more specific procedures, contains information about test animals, and their environment, anesthesia, experimental design, interventions, workflow and other overarching concepts that apply to one or more component procedures of the protocol. | There is one protocol for every project. A protocol may contain more than one procedure. | An intervention is a controlled perturbation (or treatment) that is part of the study, such as high-fat diet, ethanol in drinking water or toxin exposure. For every intervention, there should be a control (baseline). |
| Procedure | Detailed information about an experimental method, containing descriptions about equipment, reagents, solution preparation, safety issues, special definitions, formulas and data analysis. | A project may involve multiple procedures bound by a single protocol. A procedure may involve one or more assays. | |
| Assay | Analytical test that determines a range of values (preferably quantitative) for one or more biological or behavioral manifestations (traits). | A procedure may involve multiple assays. An assay quantifies one or more traits. | |
| Trait | Biological or behavioral manifestation of an individual that can be measured, quantified or scientifically categorized. A trait is a product of an organism's genome, its natural history (e.g. age), its environmental history (e.g. fostered pup) and controlled experimental perturbations (e.g. high-fat diet); when a trait is quantified for an individual or strain, it is called a characteristic (or parameter). | An assay may quantify one or more traits, and a trait may be deconstructed into component traits; a phenotvpe is determined by one or more traits. | When a trait is measured on a particular set of individuals as part of a specific scientific investigation (MPD project), the resulting set of data points is collectively called an MPD measurement. |
| MPD Measurement | Collection of data points that measure a trait in individuals of a population; measurement values span the range of biological possibilities for that population, gathered as part of a particular scientific investigation (MPD project) which follows a defined procedure and well-controlled assay. | An MPD measurement quantifies (or otherwise defines) one trait. There may be multiple. MPD measurements per project. MPD measurements are the unit of analysis (by strain and sex). Each measurement is annotated and has a set of attributes or is otherwise linked to essential information, such as: |
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| For example, a protocol might describe multi-system testing for a panel of inbred strains, which would require the description of multiple procedures, one of which might be hematology. The procedure ‘hematology’ involves multiple assays, including hematocrit and complete blood count (CBC). The CBC is an assay that measures multiple traits (WBC, RBC, etc). RBC is a quantifiable trait. The values from an assay (data points) are collectively called an MPD measurement. | It should be noted that a trait may be measured multiple times. For example RBC could be measured in more than one study or measured at multiple ages within a single study. Because one or more conditions of testing are different each time a trait is quantified for a population, the measurement receives a unique name, accession number and other attributes (above). Some redundancy in testing is encouraged for validation purposes because test conditions are rarely completely identical when animal age, environment and protocol nuances are considered. | ||