Pairwise Comparison Effort Model
Introduction
This is the mathematical model for how we're calculating time spent to map a decision space for a basic 2 way Pairwise Comparisons ("Pairwise").
This model quantifies two key aspects: expression effort , the time needed to express the preferred pairwise comparison(s) in a decision space of size, and interpretation effort , the time to review aggregated pairwise results.
This article measures how much raw human effort a legacy pairwise‑comparison survey would require to gather a portion of decision‑space knowledge that MetaPoll’s MDCT Effort Model captures in ≈ 9 minutes per voter.
To ensure the data captured by both methods was as close as possible, we force pairwise to encode the hierarchy, per‑dimension orderings, and cross‑dimension trade‑offs that MDCT stores implicitly.
Where pairwise cannot match MDCT even in principle, we call those gaps out explicitly.
Bottom line up front
Instead of going through all the background math leading up to the final calculations, we'll provide a condensed calculation of the final results for your convenience right up front.
These variables, drawn from our standardized set, focus on those directly used in and calculations.
Set Variable Values:
= 1 second = 5 seconds = 2 seconds = 1.3 = 9
Example Poll Primitive Values:
= 28
= 151
Computed Derivative Values:
= 179
Equations for Pairwise Comparison and
Voter Expression Effort
is the time required by the Expresser (Voter) to express their preferences by pairwise comparison(s) as:
Or expressed more simply with as:
Calculating using the treasury example poll:
This captures the marathon: each binary prompt forges one edge, demanding a click that logs preference
Interpretation Effort
is the time required by the Interpreter to view and understand the results from Pairwise Comparsion(s).
This covers a user exploring all Pairwise results (full option tree) and navigation (exploring results).
Calculating using the treasury example poll:
In this case is a scenario where a UI interface is not created to quickly display a ranked list of the option rankings for faster scanning.
Example MetaPoll used in calculations:
Pairwise Comparison Mathematical Framework
When mapping a decision space, the traditional approach involves pairwise comparisons, which in practice means asking people to choose between two options at a time until you've mapped the entire decision space.
This method has a fundamental problem: it doesn't scale well.
As the number of options in a decision space grows, the required comparisons multiply rapidly. Worse yet, when you consider multiple dimensions (from K₂ to K3, K4, K5, K6...) in the decision space, the computational burden explodes .
We'll begin with foundational concepts, then build to the variables and their math, using everyday language where possible while preserving rigor for technical readers.
Domains, Types, and Constraints:
Each variable has a clear domain (range of possible values) and constraints to avoid nonsense results.
Integers: ℕ₀ (non-negative, including 0), ℕ (positive, starting from 1).
Reals: ℝ (non-negative), [0,1] (fractions between 0 and 1 inclusive). ℝ ≥ 0 (positive, starting from 0, including decimals.)
Fractions lock to P₂ = 1, others zero.
Bundles span all ordered pairs across distinct dimensions, ensuring cross-talk is explicit.
Primitives, Derivatives, and Dependencies
Primitives:
Derivatives:
Dependency tree:
The option space is calculated by:
(via Theorem 1)
Wk is the threshold that activates multi-dimensional scaling variables. This accounts for flat dimensional spaces with small-W:
, else apply scaling variables.
when computed by scaling variables:
(To compute exact bundles without scaling variables, use )
is the total Options summed with the multi-dimensional bundling of :
To calculate the number of comparison prompts a voter will need to express:
Calculating (time it takes a voter to map a decision space of size) by:
Calculating by:
Variables
The full definition list of variables
: Total non-leaf nodes (dimensions and sub-dimensions). (domain: ℕ ≥ 0) Rationale: Counts the structural layers voters navigate; in example, .
: The number of leaf nodes, the options with no children (domain: ℕ ≥ 0). Rationale: This highlights endpoints that represent executable choices; in the example, .
: The number of terminal leaves (atomic options) in dimension of the decision tree (domain: ℕ ≥ 0). Rationale: accounts for the choices within each independent axis of the decision space, from low leaf numbers to high leaf numbers, forming the building blocks for cross-dimensional bundles via products like .
: L_j: The number of terminal leaves (atomic options) in dimension of the decision tree (domain: ℕ ≥ 0). Rationale: counts the indivisible choices in the j-th dimension, contributing to cross-dimensional bundles through the product , which enumerates all pairwise combinations of atomic options from distinct axes. By adding to the calculation for every preceding , we generate the full set of 2D bundles—explicit composites like "High R&D Spend ∧ Rapidly Increasing Treasury"—that capture voter trade-offs between dimensions. Summing these products over all pairs yields , quantifying the nodes needed to make cross-dimensional preferences rankable without implicit assumptions.
: The total rankable options, (domain: ℕ ≥ 0). Rationale: This sums all engageable elements (dimensions, sub-dimensions, leaves), serving as the flattened total for effort calculations; in the treasury example, .
: Average tree depth across paths (domain: ℝ ≥ 0). Rationale: Scales with layering; in example, (though not directly used here, informs broader context).
: The maximum depth, the longest path from top to bottom (domain: ℕ ≥ 0). Rationale: This deals with uneven layers; bound: but usually <20 for usability; in the MetaPoll example, . : Average branching factor, avg options per branch (sub-options per non-leaf) (domain: ℝ ≥ 0). Rationale: Measures items per layer; in example, .
: The maximum branching factor, most options per branch (domain: ℕ ≥ 0). Rationale: This spots high-effort spots; property: ; in the example, .
The power-law exponent in the scaling variable , empirically fitted as the slope of a log-log regression on observed pairs (domain: ℝ > 1). Rationale: governs bundle growth curvature, interpolating between linear scaling and quadratic explosion to capture heavy-tailed dimension sizes in MetaPoll trees, where large leaves disproportionately amplify cross-products. Across prototypes, including the treasury poll (W=179 yielding K=7,693), ranges 1.25–1.35 via Ordinary Least Squares (OLS) on log K = log ρ + α log W, we select 1.3 for conservative alignment with forecasts like K(660) ≈ 41,956 (matching direct and ratio methods). The variable is an imperfect estimation but it allows us to continuously improve accuracy via OLS as additional polls densify the data.
The scaling factor in the power-law K(W) = ρ W^α, fitted as the exponential of the log-log regression intercept on observed (W, K) pairs (domain: ℝ > 0). Rationale: sets the model's absolute scale, ensuring predictions align with real bundle counts rather than normalized abstractions, as in the treasury poll where it anchors K=7,693 at W=179. It arises from OLS as with , yielding ≈9.05 to offset baseline densities. The variable is an imperfect estimation but it allows us to continuously improve accuracy via OLS as additional polls densify the data.
: This is the threshold of options (domain: ℕ ≥ 0) before turning into a non-zero number by applying multi dimensional scaling variables via .
: Average time per voting interaction (domain: ℝ ≥ 0 in seconds, e.g., 5s for ranking). Rationale: UI-specific cost for active input.
: Average time per interpretation interaction (domain: ℝ ≥ 0 seconds, e.g., 2s for reading). Rationale: Lower cost for passive review.
: The time per comparison navigation (domain: ℝ ≥ 0, in seconds, e.g., 1s for clicks/loads). Rationale: Overhead for moving between pairwise UI ; added to account for real UI friction in both and .
: Is the number of comparisons when accounting for dimensional bundles. (domain: ℕ ≥ 0) There are two approaches to compute : 1. Exact approach: through bundle counting when having direct access to the decision space data. 2. Estimated approach: When exact decision space data is not available we use scaling variables ( and ) to estimate changed by only the variable.
: Is the number of dimensions considered when calculating bundles. (domain: ℕ ≥ 1) , is one dimensional, is two dimensional, is three dimensional and so on. By default, should be interpreted as . When , the number of bundles explode so greatly that it makes doing comparisons over them infeasible. For example: computing requires bundles, which scales very poorly. If we continue adding a 4th dimension, we must now multiply by another factor of , pushing node counts toward trillions. The prompt requirement grows on the order of where is the node count after ‑dimension bundles. MDCT supports all dimensions natively, which to put it lightly, is a massive scaling and data collection advantage over pairwise comparison limitations.
: Is the number of the base options summed with multi-dimensional bundles to get a total number of options to compare. (domain: ℕ ≥ 0) Expressed as
: Is employing the standard method for computing the number of pairwise comparisons needed to fully map a decision space of options. (domain: ℕ ≥ 0) Since we are accounting for multi-dimensionality we use in place of . Expressed as:
: The time a voter spends expressing preferences (domain: ℝ ≥ 0, in seconds). Rationale: a key metric for determining length of time to express preferences in a decision space. In the treasury example, .
: The time to read and understand aggregated results (domain: ℝ ≥ 0, in seconds). Rationale: This focuses on mapped decision space clarity of priorities, likely to be shorter than . In the treasury example, .
Axioms and Theorems
Axioms:
Axiom 1 (Completeness): Every unordered node pair demands at least one comparison.
Axiom 2 (Additivity): Rankables split into disjoint non-leaves and leaves. .
Axiom 3 (Comparison yield, binary): Each comparison forges exactly one directed edge.
Theorems:
Theorem 1 (Additivity of W): Proof: From Axiom 2, non-leaves and leaves are disjoint, and together they cover all rankables. So, the count is Corollary 1.1: For flat spaces therefore:
Theorem 2 (Prompt lower bound): Comparisons ≥ Proof: Axiom 3. Corollary 2.1: (Quadratic scaling). Comparisons = Θ(Y²), as Advanced adaptive pairwise can reduce prompts to Θ(Y log Y) by assuming transitivity, but this introduces risks of cycles (intransitive preferences) and still scales poorly with bundle-induced Y, unlike MDCT's native logarithmic handling.
Closing
From ancient symposia, where binary debates sufficed for modest scopes, pairwise gleamed with simplicity: one contest, one insight. Yet in today's systems from hundreds to millions of parameters, decision spaces governance, design, coordination at scale, pairwise comparison fractures under combinatorial pressure.
Our model unveils the toll for a treasury-like space, as quantified earlier. Why? Explicit bundling quadratics at 2D, cubics at 3D, verging exponential. MDCT, conversely, embeds trade-offs in roughly Θ(W log W) interactions, scaling seamlessly across dimensions. What graced the polis now yields to tools forged for planetary harmony. As with any model, real-world voters will test these bounds—yet the promise of logarithmic grace beckons, inviting us to reimagine coordination itself.
Appendix: How We Chose the Scaling Parameters (ρ, α, W₀)
TL;DR: Bundle growth models as K(W) = ρ W^α, cutoff at W₀ for small polls. α ≈ 1.3 from log-log empirics; ρ ≈ 9.05 calibrated to the example (W=179, K=7,693); W₀ ≈ 50 where dimensions activate. Refit with data via regression. Notation: K for bundles. Power laws suit because W expansion unevenly adds leaves/dimensions (Zipf-ish), yielding sub-quadratic sums linear in log-log. α from prototypes: slopes 1.25–1.35; 1.3 balances data, forecasts, conservatism. ρ calibration: 179^1.3 ≈ 850.5; ρ = 7,693 / 850.5 ≈ 9.05. Thus K̂(W) = 9.05 W^1.3. Cross-check (W≈660): ~41,900 bundles, consistent. W₀ curbs small-W overreach: K=0 if W ≤ 50; else power law. Adjust per audits. Refitting: Add new (log W, log K), regress for α (slope), ρ (intercept). Holdouts validate; drifts tweak α. Yields evolving K(W) for downstream C, V, T.
Metric
Pairwise value (binary‑only)
MDCT reference
Notes
Total nodes WC
7 872
179
179 base + 7 693 bundles
Prompts required PR
30 980 256
≈ 245
100 % 2‑way; one edge per prompt
Voter effort V
216 861 792 s ≈ 6.9 years
≈ 540 s (9 min)
401,595x gain
Reader effort T
30 996 000 s ≈ 359 days
≈ 450 s (7.5 min)
68,880x gain
Still missing
≥ 3‑way contingencies, indifference, incremental edits
—
Pairwise cannot support
1 Primitive Parameters
Symbol
Description
Domain
Value
L_i
Leaf count of dimension i
ℕ ≥ 0
(37, 5, 4, 72, 14, 18)
W
Original nodes (leaves + non‑leaves)
ℕ ≥ 0
179
B
Cross‑dimension bundle nodes
ℕ ≥ 0
7 693 (Eq. 1)
WC
Total nodes incl. bundles
ℕ ≥ 0
7 872 (Eq. 2)
P₂
Fraction of 2‑way prompts
[0,1]
1.0
TIMEV₂
Seconds to answer a 2‑way prompt
ℝ≥0
5
NAVTIME
Seconds per UI click
ℝ≥0
1
TIMET
Seconds to read one ranked item
ℝ≥0
2
(P₃ = P₄ = 0 in this binary‑only scenario.)
2 Derived Quantities
Symbol
Definition
Equation
Value
B
Σ cross‑dimension bundles
(1)
7 693
WC
W + B
(2)
7 872
Q
Edge count
(3)
30 980 256
E
Edges per prompt (binary)
—
1
PR
Prompts
(4)
30 980 256
t̄_prompt
Sec per prompt
(5)
7 s
V
Voter effort
(9)
216 861 792 s
T
Reader effort
(10)
30 996 000 s
2.5 What is an edge?
An edge is a single, directed preference statement captured from a prompt. In a binary survey the voter answers the question “Which of these two options do you prefer?” — that single click creates one edge in an underlying graph where every node is a poll item (WC total).
Nodes = options or bundles.
Edge A → B = “voter prefers A over B.”
Collecting edges for every unordered pair of nodes (Q = WC(WC−1)/2) guarantees the graph contains enough information to reconstruct a complete ranking equivalent to MDCT’s output. Because each 2‑way prompt yields only one edge, the prompt count equals the edge count (N = Q).
The edge concept also clarifies why 3‑/4‑way prompts were attractive earlier: a 4‑item ranking supplies 6 edges at once. But forcing all prompts to be binary keeps the UI simple—at the cost of multiplying screen count.
User experience example (binary‑only). Jane sees two cards:
Rebalance Method VS Monthly
Asset Composition VS ETH 60 % She clicks the preferred one; a green check flashes, and the system immediately presents another pair—perhaps mixing in a bundle card like Volatility Low & APY Above‑Average. Each click logs a single directed edge. A progress meter shows 0.003 % complete after the first 1 000 comparisons, hinting at the marathon ahead.
4 Domains, Types, Constraints
Timing primitives are non‑negative.
Prompt fractions:
P₂ = 1,P₃ = P₄ = 0.Bundles cover all ordered pairs of distinct dimensions.
5 Axioms, Theorems & Proofs
Axiom 1 (Completeness). Every unordered node pair must be compared ≥ 1×.
Axiom 2 (Prompt yield, binary). Each prompt contributes exactly 1 directed edge.
Theorem 1 (Prompt lower bound). Statement.
N ≥ QwhenE = 1. Proof. Direct from Axioms 1–2. ■Corollary 1.1 (Quadratic scaling).
PR= Θ(WC²). (SinceQ = WC(WC−1)/2.)
6 Derivation of Size & Time
The equations are shown twice: symbolic (xa) and numeric (xb).
6.1 Bundle count — why K = 7 693?
What is a bundle? To replicate MDCT’s ability to record cross‑dimension trade‑offs, we create a composite option for every ordered pair of leaves drawn from two different top‑level dimensions. Choosing such a card in the UI means “I prefer the combination (Leaf_i ∧ Leaf_j) over …”. For binary pairwise to learn whether people like ETH 60 % and Monthly Rebalance more than alternatives, that composite must be an explicit item.
Let * L_i = number of leaves in dimension i (see table below). * We form bundles only for unordered dimension pairs (i < j) to avoid duplicates. * Bundles are ordered within the card (the left/right order doesn’t matter for edge counting).
Number of bundles between dimensions i and j is therefore L_i × L_j. Summing across all dimension pairs gives
With 6 dimensions the explicit sum is
Computing each product:
Dimension i
Leaves L_i
Dimension j
Leaves L_j
L_i × L_j
Spending Priorities
37
Treasury Size
5
185
Treasury Pricing
4
148
Asset Composition
72
2 664
DeFi Revenue
14
518
Rebalance Strategy
18
666
Treasury Size
5
Treasury Pricing
4
20
Asset Composition
72
360
DeFi Revenue
14
70
Rebalance Strategy
18
90
Treasury Pricing
4
Asset Composition
72
288
DeFi Revenue
14
56
Rebalance Strategy
18
72
Asset Composition
72
DeFi Revenue
14
1 008
Rebalance Strategy
18
1 296
DeFi Revenue
14
Rebalance Strategy
18
252
Total
7 693
Thus
matching the value used throughout this paper.
Why stop at 2‑dimension bundles? A three‑dimension bundle would be size
L_i × L_j × L_k. The product explodes to ≈ 522,000 new nodes (Section 9), pushing the survey into “centuries per voter.”
Making K scale to W > 50
We set K=0 whenever W≤50. When above that threshold ( W > 50 ) we use the fitted K= 9 x W^{1.3}.
Choose a power-law form
K(W) = ρ Wβ \boxed{\,B(W) \;=\; \rho\,W^{\beta}\,}B(W)=ρWβ
W = total original nodes (leaf + non-leaf).
α = growth exponent (empirically ≈ 1.3).
ρ = scale constant you fit once from real polls.
Estimate ρ\rhoρ from one (or more) known polls
For our example poll we already know
W example = 179
K example = 7 693
Assuming β=1.3
ρ = BWβ = 7 6931791.3 ≈ 9.050\rho \;=\; \frac{B}{W^{\beta}} \;=\;\frac{7\,693}{179^{1.3}} \;\approx\; 0.050ρ=WβB=1791.37693≈0.050
If you add the Ethereum poll (≈ W=660,B≈W=660, B≈W=660,B≈ —let’s say you measured 30 k bundles once you flatten it), you can average the two ρ\rhoρ’s or run a quick log–log regression, but in practice they land in the same ballpark (≈ 0.04–0.06). Pick one value and document it:
ρ≈9.05,β=1.3 \boxed{\,\rho \approx 9.05,\quad\beta = 1.3\,}ρ≈9.05,β=1.3
Because K is now a smooth function of W, you can drop any value—2, 660, 10⁶—straight into the model.
7 Pairwise Prompt Walk‑Through (binary flow)
Sequential binary screens. Two cards at a time, click preferred.
Bundle encounters. Roughly one bundle card appears every few comparisons; voters must parse its dual tags.
Long‑haul reality. At 7 s per screen, solo completion = 6.9 years.
8 Capability Comparison
Feature
MDCT
Pairwise (binary)
Impact
Hierarchy preserved
✔ native tree
Manual re‑tag
Cognitive load on analyst
Cross‑dimension 2‑way trade‑offs
✔ implicit
✔ explicit bundles
Comparable after 7 872 nodes
≥ 3‑way contingencies
✔ implicit
✖ infeasible
Would need > 500 k bundles
Partial orders / indifference
✔ supported
✖ forced total order
Pairwise loses nuance or adds ties arbitrarily
Incremental edits
✔ local
✖ full re‑collect
Reboot survey for any new option
Scaling class: Binary pairwise prompts grow Θ(WC²), whereas MDCT grows Θ(W log W).
9 What’s Still Missing — Multidimensional Bundles, Indifference, and Incremental Edits
9.1 What a 3‑Dimension Bundle Would Capture
A 3‑dimension bundle like
Asset Composition · ETH 60 %ANDDeFi Revenue · APY Above‑AverageANDRebalance Strategy · Weekly
lets voters express a conditional preference that ties three separate policy knobs together. This can encode statements such as:
“I only accept high ETH exposure if we promise above‑average yield and rebalance weekly.”
9.2 How Many 3‑D Bundles Are Needed?
For each unordered triple of top‑level dimensions (i < j < k) we must create L_i × L_j × L_k composite nodes. With the six leaf counts in this treasury example:
The new total node count becomes WC₃ = WC + B₃ ≈ 530 ,464.
9.3 Edge & Prompt Explosion
Number of edges now:
Binary prompts required:
At 7 s per prompt a single voter would need ≈ 31 millennia to finish.
9.4 4‑, 5‑, 6‑Dimension Bundles
The pattern generalises: adding a 4th dimension multiplies by another factor of L_m, pushing node counts toward trillions. The prompt requirement grows on the order of Θ(WC_d²) where WC_d is the node count after d‑dimension bundles.
9.5 Why MDCT Handles High‑Order Trade‑Offs Gracefully
MDCT does not enumerate bundles. Its tree structure and score aggregation let voters express a preference path that implicitly covers all dimensional combinations without creating explicit composite nodes. Thus:
Number of dimensions tied in one statement
Pairwise prompts required
MDCT additional prompts
2
Θ(WC²) = 30 M
0 (already covered)
3
Θ(10¹¹)
0
4–6
Θ(10¹³+ )
0
9.6 Indifference (Partial Orders)
Indifference means a voter views two (or more) options as equally acceptable. MDCT lets voters skip a comparison or explicitly mark a tie, preserving a partial order. In binary pairwise, every unordered pair must still be forced into A > B or B > A to keep the edge matrix acyclic. Modeling genuine indifference requires adding duplicate prompts that check consistency or using special "tie" buttons that then need follow‑up comparisons to maintain graph connectivity—ballooning PR even further.
Practical effect: introducing a tie option typically increases prompt count by 25‑40 % in empirical studies because the algorithm must locate alternative comparison paths to break cycles.
9.7 Incremental Edits (Adding a New Option Later)
MDCT’s tree can splice a new leaf into one branch and ask only local comparisons in that subtree (Θ(log W) prompts). Binary pairwise must compare the new node against all existing WC nodes, adding WC new edges: a linear increase that quickly dominates survey length as edits accumulate.
Example: inserting a single additional treasury‑asset leaf would require 7 872 new binary prompts—~15.3 hours per voter—versus ~10 prompts in MDCT.
Takeaway: Pairwise struggles not just with dimensionality, but also with human behaviors like indecision and evolving option sets—features MDCT accommodates with logarithmic overhead.
10 Conclusion
Pairwise comparison has a venerable pedigree—going back at least to ancient Greece, where philosophers could reliably weigh two choices at a time around a small table. For that scale and era, binary pairwise was brilliantly simple: one debate, one edge, done.
Fast‑forward to modern governance and product‑design problems with hundreds of interdependent options spanning multiple dimensions. The same mechanism that once felt elegant now collapses under its own combinatorial weight. Our binary‑only model shows that faithfully encoding today’s treasury decision space would require:
≈ 30 million comparisons
≈5.6 years of nonstop effort per voter
Why? Because pairwise must explicitly compare every pair of composite nodes, and the composite count grows quadratically when you add 2‑dimension bundles, cubically for 3‑dimension bundles, and so on—approaching exponential behaviour if you keep expanding the dimensionality.
In contrast, MDCT’s hierarchical aggregation stores the same trade‑off information in Θ(W log W) prompts, scaling gracefully even if you later tie 4, 5, or 6 dimensions together. What was an elegant solution for small, flat choice sets becomes a non‑starter for today’s richly structured decision spaces.
Bottom line: Pairwise was perfect for the polis; MDCT is built for planetary‑scale coordination.
11 Full Treasury Example (MPTS)
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