Databricks Machine Learning Associate Exam - Topic 1 Question 34 Discussion

Actual exam question for Databricks's Databricks Machine Learning Associate exam

Question #: 34
Topic #: 1

[All Databricks Machine Learning Associate Questions]

A data scientist wants to efficiently tune the hyperparameters of a scikit-learn model. They elect to use the Hyperopt library's fmin operation to facilitate this process. Unfortunately, the final model is not very accurate. The data scientist suspects that there is an issue with the objective_function being passed as an argument to fmin.

They use the following code block to create the objective_function:

Which of the following changes does the data scientist need to make to their objective_function in order to produce a more accurate model?

AAdd test set validation process

BAdd a random_state argument to the RandomForestRegressor operation

CRemove the mean operation that is wrapping the cross_val_score operation

DReplace the r2 return value with -r2

EReplace the fmin operation with the fmax operation

Show Suggested Answer

Suggested Answer: D

When using the Hyperopt library with fmin, the goal is to find the minimum of the objective function. Since you are using cross_val_score to calculate the R2 score which is a measure of the proportion of the variance for a dependent variable that's explained by an independent variable(s) in a regression model, higher values are better. However, fmin seeks to minimize the objective function, so to align with fmin's goal, you should return the negative of the R2 score (-r2). This way, by minimizing the negative R2, fmin is effectively maximizing the R2 score, which can lead to a more accurate model.

Reference

Hyperopt Documentation: http://hyperopt.github.io/hyperopt/

Scikit-Learn documentation on model evaluation: https://scikit-learn.org/stable/modules/model_evaluation.html

by Marshall at Aug 12, 2025, 08:01 AM

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Lorrine

2 months ago

Not sure about removing the mean operation, that sounds risky.

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Diane

2 months ago

I think replacing r2 with -r2 makes sense for minimization.

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Denae

2 months ago

Adding a test set validation process is crucial!

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Sherill

3 months ago

Wait, can you really just swap fmin for fmax? That seems odd!

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Arlie

3 months ago

Random state is important for reproducibility, but not the main issue here.

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Marleen

3 months ago

I vaguely recall something about random_state affecting reproducibility, but I’m not convinced it would directly improve the model's accuracy in this case.

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Allene

3 months ago

I feel like we practiced a question similar to this where we had to adjust the return value. Replacing r2 with -r2 seems like it could be a good move to maximize the score.

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Celia

4 months ago

I'm not entirely sure, but I think removing the mean operation around cross_val_score might be necessary. It could be skewing the results somehow.

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Larue

4 months ago

I remember we discussed the importance of validation sets in tuning hyperparameters. Adding a test set validation process could really help improve accuracy.

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Abraham

4 months ago

Hmm, this is an interesting challenge. I think the key might be to replace the r2 return value with -r2. That could help the optimization process find a more accurate model. I'll give that a try and see how it goes.

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Pearly

4 months ago

I'm a bit confused by this one. There are a few different options, and I'm not sure which one is the right approach. I'll need to carefully read through the question and the code to try to figure out the best solution.

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Yuette

4 months ago

Alright, this is a good one. I think the issue might be with the mean operation wrapping the cross_val_score. I'll need to explore that a bit more to see if that's the root of the problem.

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Kiley

4 months ago

Okay, let's see here. The key seems to be identifying what's wrong with the objective function that's being passed to fmin. I'll need to consider the different options and think through the implications of each.

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Inocencia

5 months ago

Hmm, this looks like a tricky one. I'll need to carefully review the code and think through the potential issues with the objective function.

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