How to answer this Technical interview question about Feature Selection for Mid-Level Data Scientist?

How would you approach feature selection for a high-dimensional dataset?

A popular meme image featuring the Marvel character Thanos with the caption “A small price to pay for salvation,” commonly used to humorously express acceptance of a minor sacrifice for a greater benefit.
Data Scientist

Technical

Asked at

Google

Difficulty :

Hard

A modern, rounded square webclip or app icon with a soft gradient background, representing a mobile-friendly shortcut or digital brand identity for quick access and visual consistency.
A popular meme image featuring the Marvel character Thanos with the caption “A small price to pay for salvation,” commonly used to humorously express acceptance of a minor sacrifice for a greater benefit.

Explanation

This question evaluates your ability to reduce dimensionality and select relevant features in datasets with a large number of variables. Recruiters assess your knowledge of techniques like feature importance methods, PCA, and regularization methods. Common pitfalls include failing to mention how you handle multicollinearity or not addressing interpretability concerns. A strong answer involves discussing systematic approaches to feature selection and their trade-offs.

A popular meme image featuring the Marvel character Thanos with the caption “A small price to pay for salvation,” commonly used to humorously express acceptance of a minor sacrifice for a greater benefit.

Answer Example

I would begin by analyzing feature importance using techniques like Random Forest feature importance or mutual information scores. If multicollinearity is an issue, I would apply dimensionality reduction techniques such as PCA while balancing interpretability. For example, when working on a customer segmentation project with over 500 features, I used a combination of L1 regularization and PCA to reduce the feature set to 50 while maintaining 95% of the variance, which improved model performance and interpretability.

How it works?

Perfect applications in one click.

A popular meme image featuring the Marvel character Thanos with the caption “A small price to pay for salvation,” commonly used to humorously express acceptance of a minor sacrifice for a greater benefit.

Step 1:
Create a profile

Create your profile by uploading an existing resume or create one from scratch using our resume builder.

A popular meme image featuring the Marvel character Thanos with the caption “A small price to pay for salvation,” commonly used to humorously express acceptance of a minor sacrifice for a greater benefit.

Step 2:
Find a job post

Start searching for jobs anywhere you want and paste the job description in the box in FirstResume.

A popular meme image featuring the Marvel character Thanos with the caption “A small price to pay for salvation,” commonly used to humorously express acceptance of a minor sacrifice for a greater benefit.

Step 3:
One click .. and done

One click, and we will track your job with AI, analyse your compatibility, create your perfect resume and more, ready to apply.

That's it! Give it a go!
Get updates and career content

Subscribe to our newsletter

We frequently write blogs that help our community with their career growth! Don't miss out!

Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.
Talk to us directly

Join us on Discord

Discord is where we give updates, offer member exclusive giveaways, and help each other grow on our careers.

Your success begins here.

Get Started Now