What fairness models are available?

Three models: Equal Share divides capacity evenly (capped by demand, surplus redistributed), Historical Use allocates proportional to past cage usage, and Grant-Weighted allocates proportional to active grant funding. Each model honors committed protocol floors.

What are committed protocols?

Committed protocols represent cages that cannot be reduced — for example, animals already on study under an approved IACUC protocol. These act as a floor: no model can allocate below a PI's committed cage count.

How is the fairness score calculated?

The fairness score uses the coefficient of variation (CV) of each PI's allocation-to-demand ratio. A score of 100 means every PI gets the same fraction of their demand (perfect equity). Lower scores indicate more uneven distribution.

What is the emergency reserve?

Emergency reserve cages are held back from allocation. They cover unexpected needs: emergency breeding, quarantine, or incoming transfers. Only allocatable capacity (total minus reserve) is distributed to investigators.

ToolsConductScience tool

Core FacilityFree in-browser calculator

Allocation & Quota Planner.

Compare equal-share, historical-use, and grant-weighted fairness models to distribute vivarium cage capacity across investigators.

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Validated2026-04-08

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Facility Settings

Total cage capacity *

Emergency reserve (cages)

Fairness models *

Equal ShareHistorical UseGrant-Weighted

Investigators

PI 1

Name *

Current allocation

Demand (cages) *

Historical usage

Grant funding ($)

Committed protocols

Required fields

Investigator 1: name is required.

When to use

Annual or semi-annual cage allocation across investigators
Comparing fairness models for advisory committee review
Identifying over-committed or under-served PIs
Planning for new PI onboarding or PI departures

Do not use for

Per-diem rate calculation (use Recharge Rate Calculator)
Individual PI billing (use Per-Investigator Billing Calculator)
Space and room layout planning (use Vivarium Space Planner)

Pearl

Run all three fairness models and present the comparison to your PI advisory committee. The "fairest" model depends on institutional values, not just math.

Pearl

Set emergency reserve at 5-10% of capacity. Too low and you have no buffer; too high and you artificially constrain allocation.

Pitfall

Do not ignore committed protocols. Attempting to reallocate cages with animals already on study violates IACUC protocols and creates animal welfare issues.

Pitfall

Grant-weighted allocation can disadvantage early-career PIs. Consider a hybrid model or minimum allocation floor for new investigators.

Method

Three allocation models are compared: Equal Share (capacity / PI count, surplus redistributed), Historical Use (proportional to past cage usage), and Grant-Weighted (proportional to active grant funding). Committed protocol cages are honored as a floor. Fairness is scored using the coefficient of variation of allocation/demand ratios (100 = perfect equity). All computations run client-side.

Validated

Last validated 2026-04-08. Calculations are designed for planning and documentation support; verify procurement decisions against manufacturer specifications or institutional SOPs.

How to cite

How to Cite

ConductScience Allocation & Quota Planner (v1.29.0). ConductScience. https://conductscience.com/tools/allocation-quota-planner

NIH Guide: Policy on Managing Institutional Animal Resources (NOT-OD-05-034).

Fair Allocation of Vivarium Capacity

Vivarium capacity is finite and demand often exceeds supply. Fair allocation requires transparent, reproducible methods:

Equal share is the simplest: each PI gets the same base quota. It works well when PIs have similar programs but penalizes large, well-funded labs. Surplus from PIs who need less than their share is redistributed to PIs with unmet demand.

Historical use rewards consistency and penalizes growth. PIs who have used more cages historically get proportionally more. This avoids disruptive reallocation but can entrench inefficiency.

Grant-weighted allocation ties capacity to funding. PIs with more active grant dollars get more cages, reflecting that grant-funded work carries external obligations. This can disadvantage early-career PIs with less funding.

Committed protocols are non-negotiable. Animals already on approved protocols cannot be displaced. All models honor committed cage counts as a floor before distributing remaining capacity.

Emergency reserve (typically 5-10% of capacity) should be held back for quarantine, emergency breeding, and unexpected transfers. This prevents over-commitment and avoids crisis-mode reallocation.

Most facilities benefit from running all three models and using the comparison to guide discussion among the PI advisory committee.

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Fair Allocation of Vivarium Capacity

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