MS-DS Master of Data science Master of Data Science 5

Question 1

What is the purpose of the 'EXPLAIN' command in SQL?

Accepted Answer

To show the query execution plan chosen by the optimizer

Answer

EXPLAIN reveals the execution plan the database engine will use to run a query, helping identify bottlenecks like full table scans.

Question 2

Which ensemble method trains multiple models sequentially, where each new model corrects the errors of the previous one?

Accepted Answer

Gradient boosting

Answer

Gradient boosting builds models sequentially, with each tree fitting the residual errors (negative gradient of the loss) of the ensemble so far.

Question 3

In NLP, what does TF-IDF measure?

Accepted Answer

The importance of a term in a document relative to how common it is across all documents

Answer

TF-IDF weights terms by their frequency in a document (TF) multiplied by the inverse of how many documents contain them (IDF), boosting rare but relevant terms.

Question 4

What is a key advantage of using a data lake over a traditional data warehouse?

Accepted Answer

Ability to store raw, unstructured, and semi-structured data at low cost without requiring a predefined schema

Answer

Data lakes store data in its native format on cheap object storage, deferring schema definition to query time (schema-on-read), enabling flexible use of diverse data types.

Question 5

Which Python library provides the DataFrame abstraction and is the standard tool for tabular data manipulation in data science?

Accepted Answer

pandas

Answer

pandas provides the DataFrame and Series objects with powerful data manipulation, aggregation, and I/O capabilities for tabular data.

MS-DS Master of Data science Practice Test

MS-DS Master of Data science Practice Test

MS-DS Master of Data science Master of Data Science 5