10 Data Analyst Interview Questions and Answers


For any job in any business, the interview course of can induce main anxiousness. That’s very true for an information analyst interview, when your communication expertise and general match can be judged by folks whose jobs actually are to investigate. Yeesh. 

The greatest option to fight the pre-interview jitters is to arrange your self. That’s why we’ve curated a listing of some frequent information analyst interview questions—with solutions. 

(Many of those questions have been gathered immediately from candidates for positions at particular corporations, as listed on Glassdoor. We’ve referred to as out these corporations in parentheses.)

Let’s roll. 


Entry-Level Data Analyst 

1. Why do you need to be an information analyst?

For probably the most half, this type of query can function an icebreaker. However, typically, even when the interviewers don’t explicitly say it, they anticipate you to reply a extra particular query: “Why do you want to be a data analyst for us?”

With these self-reflective questions, there’s not likely a proper reply I can give you. There are fallacious solutions, although—pink flags for which the employer is looking out.

Answers that present you misunderstand the function are the principle “wrong” solutions right here. Equally, a solution that makes you sound wishy-washy about information evaluation can increase pink flags. 

Just a few belongings you in all probability need to get throughout embrace: 

  1. You love information. 
  2. You’ve researched the corporate and perceive why your function as an information analyst will assist it succeed. 
  3. You roughly perceive what’s anticipated of your function. 
  4. You’re assured in your resolution. 

Sample reply: I need to be an information analyst as a result of information has an inherent storytelling potential that I discover fascinating. I learn a weblog publish from considered one of your information analysts that confirmed how the sale of your merchandise has demonstrated a optimistic correlation together with your clients’ requirements of dwelling. I need to become involved with the crew that makes these insights a risk, and share these kinds of tales. 

2. Where do you see your self in 5 years?

This query is usually a bit difficult. There are land mines far and wide. For instance, you could be tempted to say you see your self operating the entire joint, however that’s clearly unwise. It demonstrates ambition and enthusiasm, however you’re all however saying you’re going to mutiny the leaders at present in cost. 

You additionally don’t need to be baited into personalizing this query an excessive amount of. It can get you off-topic very simply. They’re not taken with whether or not you need to get married in 5 years however moderately in your profession, and extra particularly your profession with the corporate. 

And, in fact, keep away from suggesting that the corporate you’re making use of to is only a pit cease or a stepping stone. In different phrases, don’t come off as indecisive or unreliable. Avoid saying issues resembling, “Well, if my band takes off, I’m hoping to tour,” or, “I’m hoping to have my own cooking show.” 

Unlike with most questions, you’re going to need to hold the reply right here fairly basic, albeit as truthful and candid as you’ll be able to with out foregoing tact. 

Sample reply: Within 5 years, I hope to have grown with the corporate and to have superior professionally towards my final objective of turning into an impactful information analyst, and, ultimately, data scientist. And, in fact, I’d wish to have a cushty work-life steadiness and pay down my money owed from faculty. 

3. Describe a time whenever you needed to persuade others. How did you get buy-in? 

The trick to this query is to show that you simply not solely persuaded others of a call, however that it was the proper resolution. 

Sample reply: As a information analyst intern at my final firm, we didn’t actually have a contemporary technique of transferring information between coworkers. We used flash drives. It took some work, however ultimately I satisfied my supervisor to let me analysis file-sharing providers that will work greatest for our crew. We tried Google Drive and Dropbox, however ultimately we settled on utilizing Sharepoint drives as a result of it built-in nicely with among the software program we have been already utilizing each day, particularly Excel. It undoubtedly improved productiveness and minimized the wasted time trying to find who had what information at what instances.

4. How do you’re feeling about information? (Swedish)

This query is a measure of your enthusiasm and ardour for the sphere; it serves as a fairly good ice breaker or an en passant between questions. Really about the one factor you don’t need to say is that you simply don’t have any type of feeling for information. 

Sample reply: I really feel that information is king. If you simply give it some thought at a sensory stage, information propels every part we do. We take sensory enter resembling sight, style, sound, scent, or contact, and we convert that information into actionable insights: solely we do it so quick we don’t even notice. But that’s precisely what we do. I’m simply the bizarre kind of one that stops to consider the sources of that information and needs to study what extra I can glean from information and how I can use it each extra effectively and successfully. 


Intermediate Data Analyst

5. Can you add 1-100 collectively proper now? (Dealer.com)

This query is easy sufficient. You might, theoretically, compute the answer just by including the numbers in sequence, like so: 1+2+3… But that is impractical and in all probability not what the interviewer is in search of. Fortunately, there’s a system referred to as a sequence sum. It’s the quantity multiplied by itself plus 1, and the ensuing answer divided by 2. 


Sample reply: Thankfully, there’s a system that may assist with this: 100(100 + 1) = 10,100; 10,100 / 2 = 5,050. 

6. What are clustered and non-clustered indexes in SQL? Explain the distinction between the 2. (Microsoft) 

Just like in textbooks, with digital information, indexes velocity up the method of looking out by means of a database. Here you simply want to elucidate the distinction between two several types of SQL indexes: clustered and non-clustered. 

Clustered and non-clustered indexes in SQL

(Note: Information for the desk from Jaipal Reddy.)

Sample reply: Whereas a clustered index is bodily saved on the desk and is, subsequently, quicker to learn, nonclustered are saved individually, which slows studying down. However, nonclustered indexes will be up to date faster and, not like clustered indexes for which there can solely be one per desk, there will be many nonclustered indexes. 

7. What is the distinction between information mining and information profiling? (Maestro Technologies)

Data mining is a course of wherein you determine patterns, anomalies, and correlations in giant information units to foretell outcomes. On the opposite hand, information profiling lets analysts monitor and cleanse information. 

Sample reply: Whereas information mining is anxious with amassing data from information, information profiling is anxious primarily with evaluating the standard of knowledge. 

8. How have you ever handled messy information previously? (Two Sigma)

Up to 80% of an information analyst’s time will be spent on cleansing information. That makes this an important idea to know. Even extra vital when you think about that, in case your information is unclean and produces inaccurate insights, it might result in expensive firm actions based mostly on false data. Yikes. That might imply bother for you. 

You must show not solely that you simply perceive the distinction between messy information and clear information but additionally that you simply used that data to cleanse the info. This article exhibits the type of workflow you could be in search of in your response, in addition to some strategies for figuring out inconsistent information and cleansing it. 

Just as with every different query the place you’re requested to explain a state of affairs you’ve encountered previously, it’s a great time to make use of the STAR technique: state of affairs, activity, motion, consequence.

Sample reply: A shopper of ours was sad with our staffing experiences, so I wanted to pore over one to see what was responsible for their chagrin. I used to be some information in a spreadsheet that contained details about when our name middle workers went to interrupt, took lunch, and many others., and I seen that the time stamps have been inconsistent: some had a.m., some had p.m., some didn’t have any specs for morning or evening, and worst of all, many of those workers have been situated in numerous time zones, so this wanted to be made extra constant as nicely. 

To resolve the a.m./p.m. dilemma, I made certain all instances have been laid out in army. This had two advantages: first, it eradicated the strings within the information and made the entire column numeric; second, it eliminated any must specify morning or evening as army time does this inherently. Next, I transformed all instances to UTC, this manner all the information was on the identical time zone. This was vital for the report I used to be engaged on as a result of in any other case the info could be offered out of order and it might trigger confusion for our shopper. Reorganizing the report’s information this manner helped enhance our relationship with the shopper, who, because of the time discrepancies, beforehand believed we have been understaffed at particular instances of day. 

Senior Data Analyst

9. How many X are in Y place? 

This query takes many types, however the premise of it’s fairly easy. It’s asking you to work by means of a mathematical drawback, normally determining the variety of an merchandise in a sure place, or determining how a lot of one thing might doubtlessly be bought someplace. Here are some actual examples from Glassdoor: 

  • “How many piano tuners are in the city of Chicago?” (Quicken Loans)
  • “How many windows are in New York City, by you estimation?” (Petco)
  • “How many gas stations are there in the United States?” (Progressive)

The concept right here is to place you in a state of affairs the place you’ll be able to’t presumably know one thing off the highest of your head, however to see you’re employed by means of it anyway. That’s the lure, although. You don’t need to simply surrender and say, nicely, gee, I don’t know. As James Patounas, affiliate director and senior information analyst at Source One, places it, “I have been asked something similar as well as asked something similar. I personally would not accept ‘you can’t really know’ as an answer; or, at least, I would not hire someone that thought this was a sufficient answer.” 

He went on: “Mathematical modeling is typically an approximation of the real world. It is rarely an exact representation.”

Basically, you need to pull the info you do have, or at the very least can approximate, and work your self by means of an answer. Let’s take the variety of home windows in New York City for instance for the pattern reply under. 

Note: Figures on this reply don’t essentially realistically replicate info; they’re approximations (there are literally 8.6 million folks in NYC, in accordance with 2017 information, for instance).

Sample reply: I consider there are about 10 million folks in New York, give or take a pair million. Assuming every of them lives in a residential constructing, with three rooms or extra, if there have been one window per room, that will make roughly 30 million home windows. I’m making a couple of totally different assumptions which might be in all probability inaccurate. For occasion, that everybody lives alone and that the typical measurement of their residences is simply three rooms with one window per room. Obviously, there can be quite a lot of variations in actuality. But I believe, by way of residences, 30 million home windows might be shut. 

Then you’d should take home windows for companies, subway rail automobiles, and private automobiles. If the typical subway automotive seats 1,000 folks, with 1 window per 2 seats, that’s 500 home windows per automotive. Somewhat extra math: I’d guess there are at the very least sufficient subway automobiles to help the entire inhabitants of New York: so 10 million divided by 1,000 comes out to 10,000. So there are one other 5 million home windows for subway automobiles. If half of all folks personal their very own automobile, that’s one other six home windows per individual, so 30 million extra home windows. I’d guess there are at the very least 100,000 companies with home windows in NYC. Let’s simply say for the sake of argument there’s a median of 10 home windows every. That’s one other million. I’m certain there’s far more than that. 

Overall, we’re at 66 million home windows (30,000,000 x 2 + 5,000,000 + 1,000,000). All of this gorgeous a lot hinges on how shut I’m to the precise inhabitants of New York City. Also, there are different locations to seek out home windows, resembling busses or boats. But that’s a begin. 

10. You have 10 luggage of marbles with 10 marbles in every bag. All however one bag has marbles which weigh 10g every. The exception’s marbles weigh 11g every. How would you identify which bag has 11g marbles utilizing a scale solely as soon as? (Google)

This query could be actually tough to determine on the spot. Fortunately, it’s a puzzle with solutions far and wide on-line.

The figuring out issue for every of those luggage of marbles is weight; thankfully, we’ve just one totally different bag. Unfortunately, we solely have one probability to weigh, so we couldn’t simply weigh every bag individually. 

Instead, we are able to resolve the issue if we put a unique variety of marbles from every bag into a brand new bag to weigh it and reverse engineer the identification of the heavier bag. 

Let’s take 1 marble from the primary bag, 2 from the second bag, Three from the third bag, and so on. This manner every bag we’ve drawn from is uniquely identifiable by the variety of marbles lacking. I’ve used my kindergarten-level illustration expertise to attract this course of. 

The marble test

The complete variety of marbles within the bag will be calculated now utilizing the sequence sum system alluded to in query 5: n(n+1)/2. If we plug the numbers in, we must always get 55. Now we’ve to multiply it by the burden of every marble, which is 10g. That means the full weight of the marbles must be 550g, in an ideal world. 

But we’re not in an ideal world. One of those luggage is totally different. Let’s say, for argument’s sake, the third bag is the one which has the heavier 11g marbles. The weights would appear to be this: 10, 20, 33, 40, 50, 60, 70, 80, 90, 100. If you weighed this, in complete, it will add as much as 553. Clearly, considered one of these luggage has botched issues up. To discover out which one, we are able to subtract 550 from 553, getting 3. In different phrases, the third bag is the odd one out. The system, then, would appear to be this: W – w(n(n+1)/2), the place W = complete weight and w = weight of every marble (besides the odd ones).

Note that we’ve labeled the luggage 1-10 based mostly on the variety of marbles taken from it. The distinction received’t essentially be this quantity, nevertheless. If the bag have been greater than 1g heavier or lighter, we’d should do extra math. Say, for instance, the odd marbles weighed 12g as an alternative; the distinction would have been 6. This nonetheless factors to the third bag as a result of we all know that the odd marbles are 2g heavier than the opposite marbles. If we divide 6 by 2, we get 3. 

Sample reply: You can discover the heavier bag of marbles by taking a unique variety of marbles, as much as 10, from every bag, putting them in a brand new bag, and weighing the consequence. For instance, you are taking 1 from the primary bag, 2 from the second, all the way in which as much as the ultimate bag, from which you’ll take all 10 marbles and place them within the new bag. If you utilize a sequence sum to seek out the variety of marbles (otherwise you’ve counted them as you positioned them within the bag), and multiply the full quantity by the bulk weight (10 on this occasion), you’ll be able to then use this quantity to seek out out the place the burden “problem” is. Weigh the marbles you’ve positioned into the brand new bag and subtract this quantity from the projected weight. The distinction would be the bag from which you took that many marbles. This is the heavier bag. 


Bonus Q&A With Source One’s Senior Data Analyst, James Patounas

What could be your prime interview query for potential information analysts? How would you reply this query? 

Suppose that you simply have been offered a flat file (Excel, CSV, and many others.) to govern and load right into a database. It incorporates tens of millions of rows. Upon loading the info into the database, you might be to carry out an evaluation, maybe constructing some kind of mathematical mannequin. While you’ll be able to’t ever be 100% assured that every part was processed and loaded appropriately, you are able to do some issues with the intention to guarantee that you’re moderately assured. Describe for me what you’ll do.

Global evaluation: Perform comparative evaluation of the uncooked file and the loaded information by [completing the following]…

  • Count the variety of rows
  • Count the variety of columns
  • Sum the numeric columns
  • Check the info sorts (i.e., if I assumed {that a} column was totally full of dates then that ought to persist)

Localized evaluation:

  • Randomly choose a couple of rows and manually examine
  • Check the distinct parts in textual fields (i.e., if classes A, B, and C exist earlier than, then that’s all I ought to see after)
  • Check frequent transcription points (i.e., information encoding might be totally different, dates are usually saved as integers previous a sure date so these could also be transformed incorrectly, and many others.)
  • Check conversions if relevant (i.e., if NA is used for non-responses for numerical values then the database received’t settle for it if we’re storing the info in a numerical area) 

What’s a query you have been requested throughout your interview, and how did you reply? 

[I was asked] “What is your greatest weakness?” I wrestle to stroll away from an fascinating drawback. 

A profession in information analytics is fast-paced, impactful, and continually altering, and now is the proper time to develop your ability set. Learn extra about Springboard’s Data Analytics Career Track now.

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