PISA definitions
PISA is an acronym for Project, Investigation, Sample, Assay and forms a layered model; each layer being a level at which metadata can be entered. As such, each PISA-level has its own metadata template. See Figure 3.
Project
The highest level of organization. It encompasses all data from a same context.
Metadata on this level will typically be defined during your project intake process.
- PhD project
- Consortium project
- Clinical Study
- Student's thesis project
Investigation
The smallest amount of samples that still form a complete story. The data that shape a complete investigation are therefore highly influenced by the research question.
Research Question | Investigation |
---|
What is the optimal setting for my microscope to measure slices of tissue X? | Microscope images of tissue X taken on different apertures, exposure time etc. |
What is the dose- and time-effect of compound Y on HepG2 cells | Measurement results of different doses and time points from both the treated and control samples. |
What is the level of CXCR4 expression in T-lymphocytes | qPCR results of expression of CXCR4- and corresponding household gene. |
Sample
Biological material that acts as a central unit in the experiment to which treatments or measurements are applied. Each investigation contains 1 to n samples. Each sample should be accompanied with proper metadata about biological origin, species, treatment, etc.
Assay
Measurements performed on samples. Each sample in an investigation is associated with 1 to n assays. Each sample in an assay should be properly annotated with (technical) metadata about machine settings, machine type, measurement date, etc. and most importantly: the pointer to the resulting data file of this sample-assay combination.