A data analyst is exploring a dataset of website session durations. A box plot of the data shows several points far beyond the upper whisker. The analyst needs to decide how to handle these points before building a regression model. What is the most appropriate first step?

Log-transform the session duration variable to reduce the impact of outliers.

Investigate the source of these points to determine if they are data entry errors or legitimate long sessions.

Remove all points beyond the upper whisker, as they are clearly errors.

Replace the outlier values with the median session duration.

Which of the following is a common method to detect duplicate records in a dataset?

Applying a random sampling technique

Sorting by a unique identifier and checking for repeats

Calculating the mean of each column

Plotting a histogram of each variable

Which practice supports continuous improvement of the data cleaning process?

Collecting feedback from data consumers about data quality issues

Avoiding documentation to save time

Freezing the cleaning process to ensure consistency

Using the same cleaning rules for all datasets

A marketing team has merged customer data from two different CRM systems. The merged dataset contains multiple records for the same customer, but the 'customer_id' field is not consistently populated across both sources. Some records have a valid ID, while others are null. The team needs a single, clean customer list. What is the most effective approach to deduplicate this data?

Assign a new unique identifier to every record and keep all of them.

Remove all records where 'customer_id' is null, then deduplicate based on the remaining IDs.

Manually review all records with a null 'customer_id' and decide on duplicates.

Deduplicate based on a combination of other attributes like full name and email address.

Which scenario best illustrates deduplication that preserves unique information?

You replace duplicate rows with a single row that has the average of all values

You delete all records that have any missing values

You randomly select one of the duplicate rows and discard the rest

Two records for the same customer have different phone numbers; you keep both numbers in one record

CertNexusCertified Data Science Practitioner (CDSP)

Domain 2Objective 2

Objective 2.2 Clean Data Sets CERTIFIED-DATA-SCIENCE-PRACTITIONER Practice Questions (Page 2)

Part of the 2.0 Extracting, Transforming, and Loading Data domain, which accounts for 17-25% of the CERTIFIED-DATA-SCIENCE-PRACTITIONER exam.

51questions here

11free pages

18concepts

17-25%of the exam

18 Concepts in This Objective

Identify and eliminate irregularities in data
Handle nulls
Remove duplicates
Correct corrupt values
Parse data
Check for corrupted data
Correct data format
Deduplicate data
Apply risk and bias mitigation techniques
Understand common forms of ML bias
Identify sources of bias
Use exploratory data analysis for outlier detection
Assess data quality
Use data auditing techniques
Mitigate bias impact
Evaluate bias outcomes
Monitor and improve data cleaning process
Adhere to data governance rules

Questions 6–10

6application · medium
A data analyst is exploring a dataset of website session durations. A box plot of the data shows several points far beyond the upper whisker. The analyst needs to decide how to handle these points before building a regression model. What is the most appropriate first step?
Select an answer first
7foundation · easy
Which of the following is a common method to detect duplicate records in a dataset?
Select an answer first
8foundation · easy
Which practice supports continuous improvement of the data cleaning process?
Select an answer first
9application · medium
A marketing team has merged customer data from two different CRM systems. The merged dataset contains multiple records for the same customer, but the 'customer_id' field is not consistently populated across both sources. Some records have a valid ID, while others are null. The team needs a single, clean customer list. What is the most effective approach to deduplicate this data?
Select an answer first
10foundation · easy
Which scenario best illustrates deduplication that preserves unique information?
Select an answer first

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