Data analyst interviews check whether you can clean, combine and summarise data in Excel. Prepare for these topics.
Core questions
How do you combine data from two tables?
Use XLOOKUP or VLOOKUP on a shared key such as an ID. For several matching rows, use FILTER or Power Query merge.
How do you summarise large data quickly?
Build a PivotTable. For formula-driven reports use SUMIFS, COUNTIFS and AVERAGEIFS.
How do you clean messy data?
TRIM for spaces, PROPER or UPPER for case, Text to Columns or TEXTSPLIT for splitting, Remove Duplicates or UNIQUE for repeats, and VALUE or DATEVALUE for text numbers and dates.
What are dynamic arrays?
Functions like FILTER, SORT, UNIQUE and SEQUENCE that return many values and spill into neighbouring cells.
How do you find outliers?
Sort or filter the column, use conditional formatting for top and bottom values, or compare each value with the average and standard deviation.
Scenario questions
You get a sales file with blanks and duplicates. What do you do?
Keep a copy of the raw data, remove duplicates by key, handle blanks by rule (fill, flag or exclude), then reconcile totals with the source.
How do you show a trend?
Group by month in a PivotTable and add a line chart.
How do you check your own work?
Match totals with the source, spot-check rows, and use simple sanity checks such as counts and min and max values.
Practise these on real datasets, and explain your steps out loud. Interviewers value the reasoning as much as the formula.