DISCOVER_MODEL

Discover a specification, interrogate its nonlinear structure, simplify it with OLS, and test it on untouched observations.

Purpose. DISCOVER_MODEL is RainbowStats' high-level model-discovery command. Supply a dependent series followed by candidate predictors. The operator coordinates the existing Genetic Model, Random Forest, and OLS tools and presents the results as a single D3 slideshow.

Syntax

DISCOVER_MODEL(LIST(Y,X1,X2,...))

Optional Genetic Model settings may be supplied in the same command:

DISCOVER_MODEL(LIST(Y,X1,X2,X3),MAX_LAG:6,MAX_VARIABLES:2,SEED:12345)

The first series in LIST is the dependent variable. The remaining series are candidate predictors.

The Discovery Pipeline

1. DiscoverGenetic search selects predictors and observation lags.
2. InterrogateRandom Forest examines nonlinear structure and recurring regimes.
3. ExplainOLS provides a parsimonious equation, inference, and diagnostics.
4. TestAn untouched chronological block provides the final reality check.

The stages answer different questions. Genetic search asks which variables and lags deserve attention? Random Forest asks does the selected relationship contain useful nonlinear structure? OLS asks can the discovered relationship be represented by a simpler statistical equation? The untouched test then asks whether the discovered relationship survives observations that were not used for selection.

What DISCOVER_MODEL Does

1. Genetic search

The Genetic Model searches predictor subsets and observation lags. Candidate specifications are evaluated using Random Forest validation on a chronological validation block. Selection therefore focuses on predictive performance rather than simply maximizing an in-sample statistic.

The Genetic Model owns the chronological train/validation/test design. The final test block remains untouched during model selection.

2. Random Forest interrogation

After selection, the chosen specification is fitted with a Random Forest using the training and validation observations. RainbowStats then compares the forest with an OLS benchmark and exposes the nonlinear structure learned by the trees.

In particular, the consolidated regime analysis identifies recurring split thresholds across the forest. These thresholds are descriptive features of the fitted model. A right-minus-left prediction contrast is not a causal effect or marginal effect.

3. OLS representation

The selected variables and lags are passed to the regression stage. OLS supplies coefficients, standard errors, t-statistics, fitted values, residual diagnostics, and a familiar parsimonious representation of the relationship discovered by the earlier stages.

Important: regression inference after data-driven model selection is exploratory. DISCOVER_MODEL does not convert predictive variable selection into a causal identification strategy.

4. Untouched test

The final slideshow returns to the chronological test observations held aside by the Genetic Model. This separates model discovery from the final assessment and helps guard against being impressed by a model only because it describes the data used to construct it.

Example: Payroll Growth

The entire discovery exercise can be written as a single RainbowStats equation:

D=DISCOVER_MODEL(SERIES_SINCE(LOGDIFF(SAME_DATE_RANGE(PAYEMS,ADPWNUSNERSA,INDPRO,CPIAUCSL)),20210101),MAX_LAG:6,MAX_VARIABLES:2,SEED:12345)

This composition performs the complete data preparation and model-discovery sequence in one line: align → transform → restrict sample → discover model.

SAME_DATE_RANGE first aligns the four source series. LOGDIFF converts the aligned series to growth rates, and SERIES_SINCE restricts the analysis to observations beginning in 2021. Because PAYEMS is the first series, it becomes the dependent variable. ADP private-payroll employment, industrial production, and CPI are supplied as candidate predictors.

MAX_LAG:6 permits the Genetic Model to search observation lags through six periods, MAX_VARIABLES:2 limits candidate specifications to at most two predictors, and SEED:12345 makes the stochastic search reproducible.

A production test of this equation selected ADP private-payroll growth at lag 3. The discovery slideshow then displayed the Genetic Model results, leading candidates, Forest-versus-OLS benchmark, consolidated Random Forest regimes, OLS regression results, residual diagnostics, and the untouched test period.

Slideshow Output

DISCOVER_MODEL is a presentation-oriented operator. Its result is a D3 slideshow, and its toJson() representation is the result of buildSlideshow().toJson().

PanelQuestion
Discovery SummaryWhat modeling process is being performed?
Genetic SelectionWhich predictors and lags survived?
Leading CandidatesWhat alternative specifications were competitive?
Forest vs OLS BenchmarkDoes nonlinear complexity improve validated performance?
Forest RegimesWhat recurring thresholds did the forest learn?
OLS ResultsCan the selected relationship be summarized parsimoniously?
Actual vs FittedHow closely does the regression describe the selected sample?
Residual AnalysisWhat structure remains in the regression residuals?
Untouched TestHow does the selected model behave on observations excluded from discovery?

Interpretation

DISCOVER_MODEL is not an automatic claim that the most complicated model is best. Its purpose is almost the opposite: let complexity earn its keep. Genetic search broadens the specification search, Random Forest reveals nonlinear structure, and OLS asks how much of the discovered relationship can be expressed with a simpler equation.

The workflow is therefore:

Candidate Data
      |
      v
GENETIC MODEL       discover variables and lags
      |
      v
RANDOM FOREST       validate and interrogate nonlinear structure
      |
      v
OLS REGRESSION      simplify, estimate, and diagnose
      |
      v
UNTOUCHED TEST      check whether the discovery generalizes

Discovery first. Complexity must validate. Inference remains explicit.

Notes

Observation lag means X at t−lag; lag 0 is contemporaneous and should not automatically be interpreted as a forecast. Random Forest regimes and prediction contrasts describe the fitted model and should not be interpreted as causal effects. Post-selection OLS inference is exploratory unless the research design independently supports stronger identification.