one factor at a time design

IRI: https://spec.industrialontologies.org/ontology/construct/OneFactorAtATimeDesign

Defined In: https://spec.industrialontologies.org/ontology/biopharma/DesignOfExperiments/

SubClass Of: bfo:OBI_0500000

Class Hierarchy

owl:Thing › bfo:OBI_0500000 › one factor at a time design

Definition

study design composed of single factor designs, each of which investigates a different selected factor while other relevant factors are held fixed

Explanatory Notes

1) The principle of an OFAT design is to vary one controlled factor through a sequence of levels while maintaining all other controlled factors at fixed baseline settings. That is, each experimental run corresponds to one experimental configuration that differs from the baseline only in the value assigned to the varied factor. 2) An OFAT design permits observation of response changes associated with one-factor changes at specified baseline settings, but it does not estimate interactions and the observed factor effect may depend on the baseline levels of the other factors. 3) OFAT designs may be used for simple process tuning, range finding, or troubleshooting when interaction effects are not a study objective. They are generally less informative than multivariable designs for screening or optimization. 4) Sequential OFAT approaches may update the baseline after identifying a favorable level for one factor and then proceed to vary another factor; the defining characteristic remains that only one factor changes per experimental sequence. 5) In an OFAT design, the dependent variable or response is declared at the level of the overall study design, while each single factor design represents a separate experimental sequence varying one selected independent variable. This allows the sequences to be interpreted as coordinated parts of one study, rather than unrelated single factor studies.

Examples

• A cell-culture study in which separate series of runs are performed to vary pH, temperature, and agitation rate individually; all other parameters remain fixed at the same baseline condition; A cell-culture study that first varies pH while keeping temperature and agitation constant; after selecting the optimal pH, temperature is varied in a subsequent series of runs

Counter-Examples

• A screening experiment where pH and feed rate are both changed in each run according to a fractional factorial design matrix; A time-course experiment in which pH, temperature, and agitation are adjusted dynamically within a single run

Adapted From

• http://purl.obolibrary.org/obo/PROCO_0000275 and https://www.6sigma.us/six-sigma-in-focus/ofat-one-factor-at-a-time/ and https://www.itl.nist.gov/div898/handbook/pri/section2/pri212.htm

Primitive Class

This class is declared primitive and it does not have necessary and sufficient condiftions defined.

Primitive Rationale

There are insufficient constructs present to create a set of necessary and sufficient conditions

Formal Axioms

First-Order Logic Axioms

OneFactorAtATimeDesign(x) → StudyDesign(x) ∧ ∃s (SingleFactorDesign(s) ∧ continuantPartOfAtAllTimes(s, x))

Semi-Formal Natural Language Axioms

if x is a ‘one factor at a time design’ then x is a ‘study design’ and x ‘has continuant part at all times’ some ‘single factor design’

Description Logic

constr:OneFactorAtATimeDesign ⊑ bfo:None

constr:OneFactorAtATimeDesign ⊑ ∃ bfo:has_continuant_part_at_all_times .⊥

SubClassOf: bfo:None

SubClassOf: bfo:has_continuant_part_at_all_times some owl:Nothing