Data Analysis Fundamentals Flashcards
7 cards from real DAC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Data Analysis Fundamentals flashcards as text
A dataset column stores customer ages but a few entries read 'unknown'. What data quality issue does this represent?
Answer: Missing values
Non-numeric placeholders like 'unknown' in a numeric field are a form of missing or null data.
Which measure of central tendency is LEAST affected by extreme outliers?
Answer: Median
The median depends only on the middle position, so extreme values barely shift it.
You need to combine two tables sharing a common customer_id column. Which operation is appropriate?
Answer: Join
A join merges rows from two tables based on a shared key column.
A chart shows sales rising every December for three years. This repeating pattern is called what?
Answer: Seasonality
Seasonality is a pattern that repeats at regular calendar intervals.
Which data type best represents a 'yes/no' survey response?
Answer: Boolean
A two-state true/false response is naturally modeled as a Boolean value.
In descriptive statistics, what does standard deviation measure?
Answer: The spread of values around the mean
Standard deviation quantifies how far values typically deviate from the mean.
A report double-counts revenue because the same order appears twice. What cleaning step fixes this?
Answer: Deduplication
Deduplication removes repeated records so each entity is counted once.