DAC Data Analysis Fundamentals 2

Question 1

A dataset column stores customer ages but a few entries read 'unknown'. What data quality issue does this represent?

Accepted Answer

Missing values

Answer

Non-numeric placeholders like 'unknown' in a numeric field are a form of missing or null data.

Question 2

Which measure of central tendency is LEAST affected by extreme outliers?

Accepted Answer

Median

Answer

The median depends only on the middle position, so extreme values barely shift it.

Question 3

You need to combine two tables sharing a common customer_id column. Which operation is appropriate?

Accepted Answer

Join

Answer

A join merges rows from two tables based on a shared key column.

Question 4

A chart shows sales rising every December for three years. This repeating pattern is called what?

Accepted Answer

Seasonality

Answer

Seasonality is a pattern that repeats at regular calendar intervals.

Question 5

Which data type best represents a 'yes/no' survey response?

Accepted Answer

Boolean

Answer

A two-state true/false response is naturally modeled as a Boolean value.

Data Analytics Certifications (DAC) Practice Test