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A data scientist is wanting to explore summary statistics for Spark DataFrame spark_df. The data scientist wants to see the count, mean, standard deviation, minimum, maximum, and interquartile range (IQR) for each numerical feature.
Which of the following lines of code can the data scientist run to accomplish the task?
The summary() function in PySpark's DataFrame API provides descriptive statistics which include count, mean, standard deviation, min, max, and quantiles for numeric columns. Here are the steps on how it can be used:
Import PySpark: Ensure PySpark is installed and correctly configured in the Databricks environment.
Load Data: Load the data into a Spark DataFrame.
Apply Summary: Use spark_df.summary() to generate summary statistics.
View Results: The output from the summary() function includes the statistics specified in the query (count, mean, standard deviation, min, max, and potentially quartiles which approximate the interquartile range).
Reference
A data scientist is working with a feature set with the following schema:
The customer_id column is the primary key in the feature set. Each of the columns in the feature set has missing values. They want to replace the missing values by imputing a common value for each feature.
Which of the following lists all of the columns in the feature set that need to be imputed using the most common value of the column?
For the feature set schema provided, the columns that need to be imputed using the most common value (mode) are typically the categorical columns. In this case, loyalty_tier is the only categorical column that should be imputed using the most common value. customer_id is a unique identifier and should not be imputed, while spend and units are numerical columns that should typically be imputed using the mean or median values, not the mode.
Databricks documentation on missing value imputation: Handling Missing Data
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A machine learning engineer has identified the best run from an MLflow Experiment. They have stored the run ID in the run_id variable and identified the logged model name as "model". They now want to register that model in the MLflow Model Registry with the name "best_model".
Which lines of code can they use to register the model associated with run_id to the MLflow Model Registry?
To register a model that has been identified by a specific run_id in the MLflow Model Registry, the appropriate line of code is:
mlflow.register_model(f'runs:/{run_id}/model', 'best_model')
This code correctly specifies the path to the model within the run (runs:/{run_id}/model) and registers it under the name 'best_model' in the Model Registry. This allows the model to be tracked, managed, and transitioned through different stages (e.g., Staging, Production) within the MLflow ecosystem.
Reference
MLflow documentation on model registry: https://www.mlflow.org/docs/latest/model-registry.html#registering-a-model
A data scientist wants to use Spark ML to impute missing values in their PySpark DataFrame features_df. They want to replace missing values in all numeric columns in features_df with each respective numeric column's median value.
They have developed the following code block to accomplish this task:
The code block is not accomplishing the task.
Which reasons describes why the code block is not accomplishing the imputation task?
In the provided code block, the Imputer object is created but not fitted on the data to generate an ImputerModel. The transform method is being called directly on the Imputer object, which does not yet contain the fitted median values needed for imputation. The correct approach is to fit the imputer on the dataset first.
Corrected code:
imputer = Imputer( strategy='median', inputCols=input_columns, outputCols=output_columns ) imputer_model = imputer.fit(features_df) # Fit the imputer to the data imputed_features_df = imputer_model.transform(features_df) # Transform the data using the fitted imputer
A data scientist has developed a random forest regressor rfr and included it as the final stage in a Spark MLPipeline pipeline. They then set up a cross-validation process with pipeline as the estimator in the following code block:
Which of the following is a negative consequence of including pipeline as the estimator in the cross-validation process rather than rfr as the estimator?
Including the entire pipeline as the estimator in the cross-validation process means that all stages of the pipeline, including data preprocessing steps like string indexing and vector assembling, will be refit or retransformed for each fold of the cross-validation. This results in a longer runtime because each fold requires re-execution of these preprocessing steps, which can be computationally expensive.
If only the random forest regressor (rfr) were included as the estimator, the preprocessing steps would be performed once, and only the model fitting would be repeated for each fold, significantly reducing the computational overhead.
Databricks documentation on cross-validation: Cross Validation
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Exam domains verified against: Official Databricks Databricks-Machine-Learning-Associate exam guide, last checked September 2026.
Master MLOps best practices and ML runtimes, including AutoML for model selection and feature engineering. Learn to create and manage feature store tables in Unity Catalog, log and track models with MLflow, and register models in the Unity Catalog registry for improved governance compared to workspace-level registries.
Sample question from this domain above: Q2
Build end-to-end ML workflows using Databricks tools and AutoML. Develop feature stores, manage model experiments with MLflow Client API, and promote models through development and production environments using aliases and tags.
Sample question from this domain above: Q3
Select appropriate algorithms and build training pipelines using Spark ML transformers and estimators. Master hyperparameter tuning with Hyperopt and grid or Bayesian search, apply cross-validation techniques, and evaluate models using classification metrics like F1 and ROC/AUC and regression metrics like RMSE and MAE.
Deploy models to endpoints for batch, real-time, and streaming inference. Use pandas for batch predictions, deploy custom models for real-time serving, and understand how Delta Live Tables support streaming inference workflows.
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