Experiment Settings

This section describes the settings that are available when running an experiment.

Display Name

Optional: Specify a display name for the new experiment. There are no character or length restrictions for naming. If this field is left blank, Driverless AI will automatically generate a name for the experiment.

Dropped Columns

Dropped columns are columns that you do not want to be used as predictors in the experiment. Note that Driverless AI will automatically drop ID columns and columns that contain a significant number of unique values (above max_relative_cardinality in the config.toml file or Max. allowed fraction of uniques for integer and categorical cols in Expert settings).

Validation Dataset

The validation dataset is used for tuning the modeling pipeline. If provided, the entire training data will be used for training, and validation of the modeling pipeline is performed with only this validation dataset. When you do not include a validation dataset, Driverless AI will do K-fold cross validation for I.I.D. experiments and multiple rolling window validation splits for time series experiments. For this reason it is not generally recommended to include a validation dataset as you are then validating on only a single dataset. Please note that time series experiments cannot be used with a validation dataset: including a validation dataset will disable the ability to select a time column and vice versa.

This dataset must have the same number of columns (and column types) as the training dataset. Also note that if provided, the validation set is not sampled down, so it can lead to large memory usage, even if accuracy=1 (which reduces the train size).

Test Dataset

The test dataset is used for testing the modeling pipeline and creating test predictions. The test set is never used during training of the modeling pipeline. (Results are the same whether a test set is provided or not.) If a test dataset is provided, then test set predictions will be available at the end of the experiment.

Weight Column

Optional: Column that indicates the observation weight (a.k.a. sample or row weight), if applicable. This column must be numeric with values >= 0. Rows with higher weights have higher importance. The weight affects model training through a weighted loss function and affects model scoring through weighted metrics. The weight column is not used when making test set predictions, but a weight column (if specified) is used when computing the test score.

Fold Column

Optional: Rows with the same value in the fold column represent groups that should be kept together in the training, validation, or cross-validation datasets.

By default, Driverless AI assumes that the dataset is i.i.d. (identically and independently distributed) and creates validation datasets randomly for regression or with stratification of the target variable for classification.

The fold column is used to create the training and validation datasets so that all rows with the same Fold value will be in the same dataset. This can prevent data leakage and improve generalization. For example, when viewing data for a pneumonia dataset, person_id would be a good Fold Column. This is because the data may include multiple diagnostic snapshots per person, and we want to ensure that the same person’s characteristics show up only in either the training or validation frames, but not in both to avoid data leakage.

This column must be an integer or categorical variable and cannot be specified if a validation set is used or if a Time Column is specified.

Time Column

Optional: Specify a column that provides a time order (time stamps for observations), if applicable. This can improve model performance and model validation accuracy for problems where the target values are auto-correlated with respect to the ordering (per time-series group).

The values in this column must be a datetime format understood by pandas.to_datetime(), like “2017-11-29 00:30:35” or “2017/11/29”, or integer values. If [AUTO] is selected, all string columns are tested for potential date/datetime content and considered as potential time columns. If a time column is found, feature engineering and model validation will respect the causality of time. If [OFF] is selected, no time order is used for modeling and data may be shuffled randomly (any potential temporal causality will be ignored).

When your data has a date column, then in most cases, specifying [AUTO] for the Time Column will be sufficient. However, if you select a specific date column, then Driverless AI will provide you with an additional side menu. From this side menu, you can specify Time Group columns or specify [Auto] to let Driverless AI determine the best time group columns. You can also specify the columns that will be unavailable at prediction time (see More About Unavailable Columns at Time of Prediction for more information), the Forecast Horizon (in a unit of time identified by Driverless AI), and the Gap between the train and test periods.

Refer to Time Series in Driverless AI for more information about time series experiments in Driverless AI and to see a time series example.

Time column settings

Notes:

  • Engineered features will be used for MLI when a time series experiment is built. This is because munged time series features are more useful features for MLI compared to raw time series features.

  • A Time Column cannot be specified if a Fold Column is specified. This is because both fold and time columns are only used to split training datasets into training/validation, so once you split by time, you cannot also split with the fold column. If a Time Column is specified, then the time group columns play the role of the fold column for time series.

  • A Time Column cannot be specified if a validation dataset is used.

  • A column that is specified as being unavailable at prediction time will only have lag-related features created for (or with) it.

  • Unavailable Columns at Time of Prediction will only have lag-related features created for (or with) it, so this option is only used when Time-Series Lag-Based Recipe is enabled.

Accuracy, Time, and Interpretability Knobs

The experiment preview describes what the Accuracy, Time, and Interpretability settings mean for your specific experiment. This preview will autmatically update if any of the knob values change. The following is more detailed information describing how these values affect an experiment.

Experiment preview

Accuracy

As accuracy increases (as indicated by the tournament_* toml settings), Driverless AI gradually adjusts the method for performing the evolution and ensemble. At low accuracy, Driverless AI varies features and models, but they all compete evenly against each other. At higher accuracy, each independent main model will evolve independently and be part of the final ensemble as an ensemble over different main models. At higher accuracies, Driverless AI will evolve+ensemble feature types like Target Encoding on and off that evolve independently. Finally, at highest accuracies, Driverless AI performs both model and feature tracking and ensembles all those variations.

Changing this value affects the feature evolution and final pipeline.

Note: A check for a shift in the distribution between train and test is done for accuracy >= 5.

Feature evolution: This represents the algorithms used to create the experiment. If a test set is provided without a validation set, then Driverless AI will perform a 1/3 validation split during the experiment. If a validation set is provided, then the experiment will perform external validation.

Final Pipeline: This represents the leveling of ensembling done for the final model (if no time column is selected) along with the cross-validation values.

Time

This specifies the relative time for completing the experiment (i.e., higher settings take longer). Early stopping will take place if the experiment doesn’t improve the score for the specified amount of iterations.

Interpretability

Specify the relative interpretability for this experiment. Higher values favor more interpretable models. Changing the interpretability level affects the feature pre-pruning strategy, monotonicity constraints, and the feature engineering search space.

Feature pre-pruning strategy: This represents the feature selection strategy (to prune-away features that do not clearly give improvement to model score). Strategy = “FS” if interpretability >= 6; otherwise strategy is None.

Monotonicity constraints: If Monotonicity Constraints are enabled, the model will satisfy knowledge about monotonicity in the data and monotone relationships between the predictors and the target variable. For example, in house price prediction, the house price should increase with lot size and number of rooms, and should decrease with crime rate in the area. If enabled, Driverless AI will automatically determine if monotonicity is present and enforce it in its modeling pipelines. Depending on the correlation, Driverless AI will assign positive, negative, or no monotonicity constraints. Monotonicity is enforced if the absolute correlation is greater than 0.1. All other predictors will not have monotonicity enforced.

Note: Monotonicity constraints are used in XGBoost GBM, XGBoost Dart, LightGBM, and Decision Tree models.

Feature engineering search space: This represents the transformers used when Note that when mixing GBM and GLM in parameter tuning, the search space is split 50%/50% between GBM and GLM.

Classification, Reproducible, and Enable GPUs Buttons

  • Classification or Regression button. Driverless AI automatically determines the problem type based on the response column. Though not recommended, you can override this setting by clicking this button.

  • Reproducible: This button allows you to build an experiment with a random seed and get reproducible results. If this is disabled (default), then results will vary between runs.

  • Enable GPUs: Specify whether to enable GPUs. (Note that this option is ignored on CPU-only systems.)