These 64 Data Analytics questions answer common beginner questions about Excel, SQL, Power BI and Reporting. Use the topic links to find a short explanation, then try the practice exercise to apply it.
Explore the ScholarLogic Data Analytics course in Bengaluru, based in BTM Layout, or try the beginner practice exercise.
Excel and spreadsheets
How do I turn a range into an Excel table?
Select the range and choose Insert Table. Confirm the headers so formulas can refer to named columns.
When is XLOOKUP useful?
Use it to return a value from a matching row, such as a product name for a SKU. Check that the lookup key is unique.
Why does Excel show a number as text?
An import can preserve leading zeros or spaces. Check the data type before converting an identifier that needs its zeros.
How can I remove extra spaces in imported names?
Use TRIM for ordinary spaces and check separately for nonbreaking spaces. Keep the original column until you verify the cleanup.
When should I use SUMIFS?
Use SUMIFS when one amount must meet several conditions, such as paid orders in one city.
How do I flag a late delivery in a spreadsheet?
Compare the delivered date with the promised date and handle undelivered orders separately.
How do I compare two lists of IDs in Excel?
Look each ID up in the other list and flag missing matches. Compare in both directions if you need both sets of exceptions.
Why does a spreadsheet sort dates incorrectly?
Check whether the column contains text dates. Convert them with the correct locale before sorting.
How can I make a spreadsheet input list consistent?
Use data validation with an allowed list. Apply the same rule to new rows.
When do I use IFERROR?
Use it when a known error has an explicit fallback. Keep unexpected failures visible so they can be investigated.
How do I bucket orders by month in Excel?
Create a date using the order year and month with day 1. Group by that date so January values from different years stay separate.
What does a weighted average show?
It gives each value influence proportional to its weight. Divide the sum of value times weight by the sum of weights.
How do I spot impossible order values?
Define checks such as negative quantity or delivery before purchase. Review flagged rows before excluding them.
How can I compare forecast and actual sales in Excel?
Use the same time periods and calculate actual minus forecast. State which sign indicates overperformance.
What should a spreadsheet audit tab contain?
Record source counts, totals, refresh dates, assumptions and exceptions so another reader can reproduce the checks.
How do I preserve leading zeros in a CSV import?
Import identifier columns as text before Excel infers a number type. Formatting after import cannot recover lost zeros.
SQL for analysis
What is a SQL primary key?
It identifies a table row uniquely and cannot be null. A key may consist of several columns.
What is a composite join key?
It joins on multiple fields, such as store ID plus receipt number, when neither identifies a row alone.
Why does a comparison with NULL not return true?
NULL represents an unknown or missing value in SQL. Use IS NULL to test for it.
When should I use CASE in a SQL report?
Use it to label or group records by a rule, such as marking orders over a threshold.
How do I calculate a running total in SQL?
Use SUM as a window function ordered by date and a stable tie-breaker. Specify the intended row frame.
How do I compare each month with the previous month in SQL?
Aggregate to month first, then use LAG ordered by month. Fill missing calendar months if a gap must count as zero.
How do I select the latest status for each order?
Rank events per order by timestamp and a tie-breaker, then keep the first. Do not pick a status by alphabetical maximum.
What is a SQL date spine?
It is a complete series of dates used to show dates that have no matching events.
How do I report distinct buyers by week?
Assign each order to a week in the reporting timezone, then count distinct buyer IDs within each week.
What is a SQL anti-join useful for?
It finds rows with no matching key in another table, such as unreconciled records. NOT EXISTS is one way to express it.
Why can filtering a LEFT JOIN remove unmatched rows?
A WHERE condition on a right-table column can reject the null rows. Put match conditions in ON when unmatched left rows must survive.
How do I test for multiple rows per key in SQL?
Group by the proposed key and keep groups whose count is greater than one. Check if those groups are valid detail rows.
When should I cast a value in SQL?
Cast when the operation needs a different type, such as decimal division or date comparison. Inspect failed conversions.
How do I avoid integer division in a SQL rate?
Convert a numerator or denominator to a decimal type before dividing. Handle a zero denominator explicitly.
Why should SQL report dates use half-open ranges?
Using at least the start and before the next boundary includes all timestamps in the period without guessing the last instant.
How do I compare two versions of a SQL output?
Compare row counts and totals first, then match by business key to detect missing rows and changed values.
Power BI modelling
What is a fact table in Power BI?
It holds events or measurements such as order lines, along with keys that connect them to dimensions.
What is a dimension table in a Power BI model?
It describes entities such as products or dates so users can group and filter facts.
Why does the one side of a model relationship need unique keys?
A repeated key on that side breaks the intended one-to-many relationship. Resolve duplicates according to the business rules.
What is a disconnected table in Power BI?
It has no model relationship. A measure can read its selection to change a calculation without directly filtering fact rows.
What does filter context mean in DAX?
It is the set of filters active for a calculation, including the current visual cell, slicers and relationship filters.
What does CALCULATE do in DAX?
It evaluates an expression in modified filter context. Test which filters are added or replaced.
When should I use DIVIDE in DAX?
Use it for ratios where the denominator may be zero. Its default result in that case is blank.
When is SUMX useful in Power BI?
Use SUMX to evaluate a row expression, such as quantity times unit price, and then sum the results.
Why can a Power BI grand total differ from the sum of displayed percentages?
The measure is evaluated again in the total context. A ratio of overall totals can differ from adding individual ratios.
What is a drill-through page in Power BI?
It opens a detail page filtered by a value selected on another page, such as one product category.
What is row-level security in Power BI?
It restricts the rows visible to users based on role rules. Test with a representative role before sharing.
Why should currency use a suitable numeric type?
Consistent precision prevents rounding surprises. Match the data type and rounding rules to how the business records amounts.
What is the difference between appending and merging in Power Query?
Append stacks rows from tables. Merge joins related columns according to keys.
What does unpivot do in Power Query?
It turns repeated columns, such as one per month, into attribute and value rows.
How do I check the effect of a Power Query step?
Compare row counts, types and sample values before and after the step. Investigate unexpected changes.
What should a refresh error message tell an analyst?
Identify the failing query or step and the affected source. Check credentials, schema changes and the last successful refresh.
Reporting decisions
How do I choose a useful comparison period?
Choose periods with comparable length and business conditions. Call out seasonality, holidays and incomplete dates.
When should I report a median?
Use it when extreme values pull the mean away from a typical observation, such as a few unusually long delivery times.
How do I distinguish a rate from a count?
A rate divides events by an eligible population or exposure. Show both numerator and denominator so it can be interpreted.
What is a percentage point change?
It subtracts one percentage from another. An increase from 10% to 12% is two percentage points.
How do I show uncertainty in a dashboard?
Label provisional figures and small samples. Include a range or interval when you have a defensible way to estimate one.
What should a chart title say?
State the metric, group or period and the main question. Use a subtitle for important filters or definitions.
Why should a bar chart usually start at zero?
Bar length represents magnitude. A truncated axis can visually exaggerate small differences.
When is a scatter plot useful in analysis?
It shows how two numeric variables vary together and reveals clusters or outliers. It cannot establish causation on its own.
How do I decide whether to exclude an outlier?
Check if it is an error, valid extreme or separate population. Document the rule and compare results with and without it.
How do I report a metric definition clearly?
State the numerator, denominator, eligible records, time window and source. Add an example calculation.
How should I track dashboard data freshness?
Show the source period and the last successful refresh separately. Alert readers if expected data has not arrived.
What should a reconciliation table show?
List expected, observed and difference for each key or period, then include an exception reason when known.
What is a drill-down in a business dashboard?
It moves through levels such as year, quarter and month within the same hierarchy.
How can I test a dashboard before sharing it?
Compare known totals and edge cases, try filters and confirm empty states. Ask a second person to reproduce one metric.
How do I explain a surprising dashboard result?
Verify the data first, describe the change with a baseline, and separate observed evidence from possible explanations.
What should a beginner analyst show alongside a dashboard?
Include the business question, source notes, checks and a short explanation of the decision the report supports.
For further reading, see the official reference and compare ScholarLogic’s six courses.
