dowhy 0.11

Key Features

DoWhy supports the following causal tasks:

• Effect estimation (identification, average causal effect, conditional average causal effect, instrumental variables and more)

• Quantify causal influences (mediation analysis, direct arrow strength, intrinsic causal influence)

• What-if analysis (generate samples from interventional distribution, estimate counterfactuals)

• Root cause analysis and explanations (attribute anomalies to their causes, find causes for changes in distributions, estimate feature relevance and more)

For more details and how to use these methods in practice, checkout the documentation at https://py-why.github.io/dowhy

Example: Effect identification and estimation

Most causal tasks in DoWhy only require a few lines of code to write. Here, we exemplarily estimate the causal effect of a treatment on an outcome variable:

from dowhy import CausalModel
import dowhy.datasets

# Load some sample data
data = dowhy.datasets.linear_dataset(
    beta=10,
    num_common_causes=5,
    num_instruments=2,
    num_samples=10000,
    treatment_is_binary=True)

A causal graph can be defined in different way, but the most common way is via NetworkX. After loading in the data, we use the four main operations for effect estimation in DoWhy: model, identify, estimate and refute:

# I. Create a causal model from the data and given graph.
model = CausalModel(
    data=data["df"],
    treatment=data["treatment_name"],
    outcome=data["outcome_name"],
    graph=data["gml_graph"])  # Or alternatively, as nx.DiGraph

# II. Identify causal effect and return target estimands
identified_estimand = model.identify_effect()

# III. Estimate the target estimand using a statistical method.
estimate = model.estimate_effect(identified_estimand,
                                 method_name="backdoor.propensity_score_matching")

# IV. Refute the obtained estimate using multiple robustness checks.
refute_results = model.refute_estimate(identified_estimand, estimate,
                                       method_name="random_common_cause")

DoWhy stresses on the interpretability of its output. At any point in the analysis, you can inspect the untested assumptions, identified estimands (if any), and the estimate (if any). Here’s a sample output of the linear regression estimator:

For a full code example, check out the Getting Started with DoWhy notebook.

You can also use Conditional Average Treatment Effect (CATE) estimation methods from EconML, as shown in the Conditional Treatment Effects notebook. Here’s a code snippet.

from sklearn.preprocessing import PolynomialFeatures
from sklearn.linear_model import LassoCV
from sklearn.ensemble import GradientBoostingRegressor
dml_estimate = model.estimate_effect(identified_estimand, method_name="backdoor.econml.dml.DML",
                control_value = 0,
                treatment_value = 1,
                target_units = lambda df: df["X0"]>1,
                confidence_intervals=False,
                method_params={
                    "init_params":{'model_y':GradientBoostingRegressor(),
                                   'model_t': GradientBoostingRegressor(),
                                   'model_final':LassoCV(),
                                   'featurizer':PolynomialFeatures(degree=1, include_bias=True)},
                    "fit_params":{}})

Example: Graphical causal model (GCM) based inference

DoWhy’s graphical causal model framework offers powerful tools to address causal questions beyond effect estimation. It is based on Pearl’s graphical causal model framework and models the causal data generation process of each variable explicitly via causal mechanisms to support a wide range of causal algorithms. For more details, see the book Elements of Causal Inference.

Complex causal queries, such as attributing observed anomalies to nodes in the system, can be performed with just a few lines of code:

import networkx as nx, numpy as np, pandas as pd
from dowhy import gcm

# Let's generate some "normal" data we assume we're given from our problem domain:
X = np.random.normal(loc=0, scale=1, size=1000)
Y = 2 * X + np.random.normal(loc=0, scale=1, size=1000)
Z = 3 * Y + np.random.normal(loc=0, scale=1, size=1000)
data = pd.DataFrame(dict(X=X, Y=Y, Z=Z))

# 1. Modeling cause-effect relationships as a structural causal model
#    (causal graph + functional causal models):
causal_model = gcm.StructuralCausalModel(nx.DiGraph([('X', 'Y'), ('Y', 'Z')]))  # X -> Y -> Z
gcm.auto.assign_causal_mechanisms(causal_model, data)

# 2. Fitting the SCM to the data:
gcm.fit(causal_model, data)

# Optional: Evaluate causal model
print(gcm.evaluate_causal_model(causal_model, data))

# Step 3: Perform a causal analysis.
# results = gcm.<causal_query>(causal_model, ...)
# For instance, root cause analysis:
anomalous_sample = pd.DataFrame(dict(X=[0.1], Y=[6.2], Z=[19]))  # Here, Y is the root cause.

# "Which node is the root cause of the anomaly in Z?":
anomaly_attribution = gcm.attribute_anomalies(causal_model, "Z", anomalous_sample)

# Or sampling from an interventional distribution. Here, under the intervention do(Y := 2).
samples = gcm.interventional_samples(causal_model, interventions={'Y': lambda y: 2}, num_samples_to_draw=100)

The GCM framework offers many more features beyond these examples. For a full code example, check out the Online Shop example notebook.

For more functionalities, example applications of DoWhy and details about the outputs, see the User Guide or checkout Jupyter notebooks.

Citing this package

If you find DoWhy useful for your work, please cite both of the following two references:

• Amit Sharma, Emre Kiciman. DoWhy: An End-to-End Library for Causal Inference. 2020. https://arxiv.org/abs/2011.04216

• Patrick Blöbaum, Peter Götz, Kailash Budhathoki, Atalanti A. Mastakouri, Dominik Janzing. DoWhy-GCM: An extension of DoWhy for causal inference in graphical causal models. 2022. https://arxiv.org/abs/2206.06821

Bibtex:

@article{dowhy,
  title={DoWhy: An End-to-End Library for Causal Inference},
  author={Sharma, Amit and Kiciman, Emre},
  journal={arXiv preprint arXiv:2011.04216},
  year={2020}
}

@article{dowhy_gcm,
    author = {Bl{\"o}baum, Patrick and G{\"o}tz, Peter and Budhathoki, Kailash and Mastakouri, Atalanti A. and Janzing, Dominik},
    title = {DoWhy-GCM: An extension of DoWhy for causal inference in graphical causal models},
    journal={arXiv preprint arXiv:2206.06821},
    year={2022}
}

Issues

If you encounter an issue or have a specific request for DoWhy, please raise an issue.

Contributing

This project welcomes contributions and suggestions. For a guide to contributing and a list of all contributors, check out CONTRIBUTING.md and our docs for contributing code. Our contributor code of conduct is available here.