88 lines
2.2 KiB
Markdown
88 lines
2.2 KiB
Markdown
---
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title: Statistical Modeling for Construction Estimating
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tags:
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- topic/construction
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- topic/estimating
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- topic/math/statistics
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- type/cross-topic
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---
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# Statistical Modeling for Construction Estimating
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Cross-topic of [[statistical-modeling]] and [[construction-estimating]].
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%%
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## TALK
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This note should discuss the application of modeling in estimating,
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including what is already common practice (e.g. average run lengths),
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as well as the potential for more robust models.
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Models are useful where information is limited,
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and where more precise methods would be suboptimal[^1].
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[^1]: see [[risk-management-for-construction-estimating]].
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Specific examples should generally be relegated to linked notes.
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This note may contain common objections
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and arguments disputing them,
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but the reader should be assumed not to be especially skeptical.
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%%
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## Bayesian Takeoff
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#### User Story
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Frank is estimating a 20-story high rise
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and notices that their are roughly, but not exactly,
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the same number of receptacles in the corridors of levels 2 to 19.
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Frank starts a new takeoff for duplex receptacles,
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typical of levels 2 to 19.
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He counts and inputs quantities for 3 levels,
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each adjusts the prior to calculate the expected quantity for all 18 levels.
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## Stochastic Branch Takeoff
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generate a BOM from point loads distributed in a space.
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```yaml
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- x: 302.84
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y: 2364.47
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kW: 5.3
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voltage: 277
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phases: 1
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...
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```
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determine relative impact of factors
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* allowable voltage drop
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## Methods
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> [!cite] Reddit u/mightofmerchants
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> ![[spatial-sampling.gif|300x300]]
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* Poisson disc sampling
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* Delunay triangulation
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* Voronoi diagrams
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%% TODO: link paper on procedural generation of single family homes %%
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## Average Distance Given Area
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Holding area constant,
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average taxicab distance between points
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varies greatly with the aspect ratio of the space.
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Weighted by a probability distribution
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an average length and confidence could be given for any known area.
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[[sigmoid-functions]]
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Maximum area per floor is sometimes capped by
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[[ibc-construction-types]] or [[ibc-occupancy-classifications]],
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either directly (see [[ibc_ch05]], [[ibc_ch09]]),
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or by maximum travel distance (see [[ibc_ch10]]).
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Stairwells are expensive. There are usually only 2 or 3.
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