Ericsson Data Analytics Interview Questions & Answers
Curated interview practice questions with answers. These are practice scenarios, not a verified list of past interview questions.
About Ericsson hiring for Data Analytics roles
Ericsson is a Swedish telecommunications company that provides network equipment, software and services for mobile operators, including 4G and 5G radio, core networks and network management. In India it supports major telecom operators with network deployment and managed services, and runs research and development centres. It hires telecom engineers, software engineers, testers and network engineers.
For Data Analytics roles, this Ericsson practice set focuses most on Statistics and Case Studies (7), Power BI (6), Data Cleaning (5), Dashboards and KPIs (5). It has 10 easy, 27 medium, 3 hard questions, so you can start easy and work up to the harder ones.
Company type
Telecom
Headquarters
Stockholm, Sweden
Main India offices
Gurugram, Bengaluru, Chennai, Noida, Kolkata
Ericsson Data Analytics interview process
Online assessment (aptitude + technical)
Technical interview
Managerial round
HR round
Typical pattern based on public candidate experiences. Rounds vary by role, team and year.
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01
What is the difference between an outlier and a data error?
An outlier is a genuine but unusual value, such as a bulk corporate order of 50 laptops; it is real and may be important. A data error is an incorrect value, such as an age of 250 or a price entered in paise instead of rupees. Errors should be fixed or removed. Outliers should be investigated and often kept, perhaps analysed separately or with median-based metrics so they do not distort averages.
Field parameters let report users switch which measure or dimension a visual uses through a slicer. For example, one chart can switch between Sales, Profit and Quantity, or between grouping by Region, Category and Channel. This replaces many duplicate visuals or bookmark tricks, keeping the report lighter and easier to maintain. They are created from Modeling, New parameter, Fields, which generates a small table behind the slicer.
03
Write SQL to flag rows that fail basic validation rules in a customer table.
SELECT customer_id,
CASE WHEN email IS NULL OR email NOT LIKE '%_@_%._%' THEN 1 ELSE 0 END AS bad_email,
CASE WHEN LENGTH(pincode) <> 6 THEN 1 ELSE 0 END AS bad_pincode,
CASE WHEN signup_date > CURRENT_DATE THEN 1 ELSE 0 END AS future_signup,
CASE WHEN age NOT BETWEEN 18 AND 100 THEN 1 ELSE 0 END AS bad_age
FROM customers;
-- sum each flag to report the error rate per rule
Table calculations are computed on the aggregated results already in the view, not on the underlying rows. Examples are running total, percent of total, difference from previous, rank and moving average. Their result depends on the direction and partition you set with Compute Using, for example table across or by specific dimensions. They are quick to add from Quick Table Calculation, but incorrect Compute Using settings are a frequent cause of wrong numbers.
05
Write pandas code to fill missing values in a column with the median of each group.
# Fill missing delivery_days with the median for that city
df['delivery_days'] = (
df['delivery_days']
.fillna(df.groupby('city')['delivery_days'].transform('median'))
)
# Rows in a city with no values at all stay NaN; fall back to overall median
df['delivery_days'] = df['delivery_days'].fillna(df['delivery_days'].median())
06
How would you design a sales dashboard for executives?
Start with KPIs (revenue, margin, growth), add trend and comparison to target, allow drill-down by region and product, keep it to one screen and test with the audience.
Totals in DAX are not the sum of visible rows; the measure is recalculated in the total's filter context. A measure like a distinct count, a ratio or an IF condition can give a different result at total level. If the business wants the sum of row values, iterate explicitly, for example SUMX ( VALUES ( Product[Name] ), [My Measure] ). Confirm with stakeholders which total is correct before changing it.
A p-value is the probability of seeing a result at least as extreme as yours if the null hypothesis, usually no effect, were true. A p-value of 0.03 means that if the new page truly made no difference, results this strong would appear only about 3 percent of the time by chance. Below a chosen threshold such as 0.05 we reject the null. It is not the probability that the hypothesis is true.
10
Many reporting queries in your team use SELECT DISTINCT to remove duplicate rows. What is the risk?
SELECT DISTINCT often hides a real problem, such as a join on the wrong key or a one-to-many join that multiplies rows. The output looks clean, but sums computed before the DISTINCT, or legitimate repeated rows, can be wrong, and DISTINCT adds a costly sort on large tables. Instead, find why duplicates appear, fix the join or aggregate the child table first, and add a uniqueness test on the key.
11
What is a holdout group and why do teams keep one?
A holdout group is a small share of users, often 5-10%, kept out of a feature or of all marketing campaigns for a long time. Comparing them with everyone else shows the cumulative long-term impact, which individual short tests miss, and checks whether many small wins really add up. For example, a notification holdout shows whether push messages raise monthly retention or just shift activity earlier.
SELECT
a.variant,
COUNT(DISTINCT a.user_id) AS users,
COUNT(DISTINCT o.user_id) AS converters,
ROUND(100.0 * COUNT(DISTINCT o.user_id)
/ COUNT(DISTINCT a.user_id), 2) AS conversion_pct
FROM experiment_assignments a
LEFT JOIN orders o
ON o.user_id = a.user_id
AND o.order_ts >= a.assigned_ts
WHERE a.experiment_id = 'checkout_v2'
GROUP BY a.variant;
15
What is statistical significance vs practical significance?
Vanity metrics look impressive but do not help decisions or reflect real value, such as total app downloads, total registered users or social media likes. They usually only go up. Better alternatives are actionable metrics such as active users, retention by cohort, conversion rate and revenue per user. A quick test: if the number changed, would anyone do anything differently? If not, it probably does not belong on the main dashboard.
17
Average delivery time improved by 4 minutes, but customer complaints about late deliveries went up. How do you investigate?
An average can improve while the tail gets worse. I would look at the distribution: median, 90th and 95th percentiles and the share of orders beyond the promised time. Then break it down by city, time slot and restaurant to see where late orders cluster. Also check whether promised times changed, whether complaint tracking changed and whether a few very fast orders pulled the mean down.
18
Marketing wants to A/B test two email subject lines on a list of 2,000 subscribers. What do you advise?
With 1,000 per group and a typical click rate of 3%, only a very large difference, roughly 70% relative or more, would be detectable, so a small real lift would look like noise. I would suggest testing on a larger send, pooling several campaigns, or using open-to-click rate with a bigger effect. If they still run it, report the confidence interval and treat the result as directional.
A Type I error is a false positive: concluding there is an effect when there is none, for example launching a feature that does not actually lift sales. Its probability is alpha, often 0.05. A Type II error is a false negative: missing a real effect, with probability beta. Power is 1 minus beta. Larger samples reduce Type II errors, and the business cost of each mistake should guide which one you guard against more.
20
Tell me about a time you found a serious data quality issue.
Situation: while building a returns report I noticed one warehouse had zero returns for three months. Task: confirm whether it was real. Action: I compared with the source system and found its return codes had changed after a software update, so my filter missed them. I informed the data owner, updated the mapping and back-filled the history. Result: the corrected report showed that warehouse had the highest return rate, which led to a packaging review.
21
Write SQL to find the number of days between each customer's consecutive orders and their average gap.
WITH gaps AS (
SELECT customer_id,
order_date,
order_date - LAG(order_date) OVER (
PARTITION BY customer_id ORDER BY order_date) AS days_since_prev
FROM orders
)
SELECT customer_id,
COUNT(*) AS orders,
AVG(days_since_prev) AS avg_gap_days
FROM gaps
GROUP BY customer_id
HAVING COUNT(*) > 1;
-- order_date is DATE (PostgreSQL); use DATEDIFF in other databases
22
Write SQL to generate a simple date dimension for 2026.
-- PostgreSQL syntax
CREATE TABLE dim_date AS
SELECT
TO_CHAR(d, 'YYYYMMDD')::INT AS date_key,
d::DATE AS full_date,
EXTRACT(YEAR FROM d) AS year,
EXTRACT(QUARTER FROM d) AS quarter,
EXTRACT(MONTH FROM d) AS month_no,
TO_CHAR(d, 'Mon') AS month_name,
TO_CHAR(d, 'Dy') AS weekday,
EXTRACT(ISODOW FROM d) IN (6, 7) AS is_weekend
FROM GENERATE_SERIES(DATE '2026-01-01', DATE '2026-12-31', INTERVAL '1 day') AS d;
A story is a sequence of sheets or dashboards, called story points, that walk an audience through an analysis step by step, like slides. Each point can keep its own filters and selections and has a caption explaining the insight. It is useful for presenting findings such as why churn rose, moving from the headline number to segments and recommendations. For everyday monitoring, a regular dashboard is better than a story.
LET assigns names to intermediate results inside a single formula, for example =LET(sales, SUM(D2:D100), cost, SUM(E2:E100), (sales-cost)/sales). It makes long formulas readable and faster, because a repeated sub-calculation is evaluated once instead of several times. It is especially useful with dynamic arrays, where the same FILTER result might otherwise be recalculated three or four times in one nested formula.
Sampling bias occurs when the sample does not represent the population, so conclusions do not generalise. Common types: selection bias, such as surveying only app users about website issues; survivorship bias, studying only customers who stayed; non-response bias, when unhappy customers skip surveys; and convenience sampling, using whoever is easiest to reach. Random sampling, stratification and weighting help reduce it.
Check the components: sessions may have fallen, for example after cutting paid campaigns, which removes low-intent traffic and lifts the rate without new sales. Average order value may have dropped because of discounts or a mix shift towards cheaper products. Also check whether conversion definitions or tracking changed. Revenue equals sessions times conversion rate times AOV, so break down the change across those three factors by channel.
A north star metric is the single measure that best captures the value a product delivers to customers and predicts long-term growth, such as weekly active learners for an education app or orders delivered for a delivery service. It aligns teams around one outcome. It should be supported by input metrics that teams can influence, such as activation rate and repeat usage, and balanced with guardrails like cost or quality.
32
Write pandas code to extract month name, weekday and hour from a timestamp column.
A calculated field lives inside a PivotTable and works on summarised data; a helper column is a normal column of formulas that feeds the PivotTable or other formulas.
Readers scan from the top-left, so place the most important KPIs as cards across the top, then trend charts, then breakdowns and detail tables at the bottom. Group related visuals, align them on a grid and keep consistent spacing, fonts and colours. Put filters in one consistent place. Limit a page to roughly five to eight visuals that answer related questions, and give the page a clear title stating its purpose.
35
Write a Python function that reads all Excel files in a folder and combines them into one DataFrame.
I would ask which decisions each new visual supports and how often they will look at it. Usually a few are essential and the rest are nice to have. I would propose keeping the main page focused on core KPIs and moving detail into drill-through pages, tooltips or a separate analysis tab. Showing a quick mock-up of both versions helps them see that the cleaner page answers questions faster.
37
A marketing campaign shows more sales. How do you prove it worked?
Browser tracking prevention, ad blockers and consent banners mean many visits are not fully tracked, so analytics undercounts users and conversions and breaks multi-session journeys. Under India's DPDP Act and similar laws, you need valid consent for non-essential tracking. Teams respond with consent mode modelling, first-party and server-side tagging, logged-in user IDs and reconciling analytics with backend orders, and they treat analytics numbers as estimates rather than exact counts.
39
What does the IF function do and how do you nest it?
Convert timestamps to the business time zone before deriving the date. IST is UTC plus 5 hours 30 minutes, so an order at 20:00 UTC belongs to the next day in IST. In SQL use AT TIME ZONE or CONVERT_TZ, and in pandas use tz_localize('UTC') followed by tz_convert('Asia/Kolkata'). Store raw UTC, add a local date column in the model, and document which one each report uses.
Tips to crack the Ericsson Data Analytics interview
Revise computer networks, TCP/IP, and basics of mobile communication such as LTE and 5G architecture before interviews.
Practise programming in C, C++, Java or Python, and be ready to solve simple coding and debugging problems.
Learn about Ericsson's role in 5G rollouts in India to discuss the industry and your interest in telecom.
Keep a one-minute story ready for every project on your CV: problem, your part, tools, result.
Practise the hard questions on this page aloud; Ericsson interviewers usually ask follow-ups on your first answer.
Frequently asked questions
How many rounds are there in the Ericsson Data Analytics interview?
Candidates usually go through 4 stages: Online assessment (aptitude + technical); Technical interview; Managerial round; HR round. The exact rounds change with the role, team, location and your experience, so confirm the process with the recruiter.
Which topics should I prepare for the Ericsson Data Analytics interview?
This practice set leans on Statistics and Case Studies (7), Power BI (6), Data Cleaning (5), Dashboards and KPIs (5). Revise those first, then practise explaining one or two of your own projects end to end, because most Ericsson interviewers ask you to walk through real work.
Are these the exact questions asked at Ericsson?
No. These are curated practice questions that match the skills and difficulty usually tested in telecom interviews like Ericsson's. They are not a leaked or verified list of past questions.
Where does Ericsson hire Data Analytics professionals in India?
Ericsson has large teams in Gurugram, Bengaluru, Chennai, Noida, Kolkata. Openings and locations change often, so check the Ericsson careers page and filter by city and experience.