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Behavioral
2 years ago
I am interested in the learning and development you gained at your previous position, which you feel will be quite valuable at ThoughtWorks
Data Scientist

ThoughtWorks

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2 years ago
Product Case
2 years ago
In what way do you measure the retention rate of a product?
Data Scientist

ThoughtWorks

OpenDoor

Faire

If it's a subscription based product,  After usage of the product I check how many users continue with the subscriotion after 7 days, 15days, 1 month, 3 months and 6 month. The % of users who continue to have the subscriotion after the above time periods are the retained users


For non subscription products, I can check weekly or monthly retention by finding % of users who come back to product the week or month after using

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2 years ago
BehavioralTechnical
2 years ago
What did you learn from a craft conference you attended recently?
Data ScientistData Engineering ManagerUX DesignerEngineering Manager

ThoughtWorks

LendingClub

Bill.com Logo

Bill.com

The last conference I attended was the Open Source Security Foundation. As I was leading the Dart & Flutter security program I wanted to learn about the innovations, tooling and services that other open source projects were using.

There were interesting conferences for tooling to sign artifacts with a single command and how the open source community was working in tooling to build, sign and release artifacts in a secure way for everyone using GitHub.

I learned that there were many technical innovations that I could use to speed up the Flutter Security Program, for example implementing secure build workflows using github actions. I also met several people working on similar projects and took the opportunity to share our lessons learned and challenges. Later on the connections with the open source security foundation proved very useful during technical reviews and collaborations.

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2 years ago
ML Knowledge
2 years ago
How would you explain an ROC curve to a non-technical stakeholder? In what situations would you prefer bagging over boosting?
Data ScientistMachine Learning Engineer

ThoughtWorks

Zillow Logo

Zillow

Wish Logo

Wish

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2 years ago
Coding
2 years ago
Show how you'd write a function to produce all permutations that are anagrams of a string.
Data Scientist

ThoughtWorks

Lattice Logo

Lattice

Pandora Logo

Pandora

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2 years ago
SQL
2 years ago
What factors do you think may impact the accuracy of measuring monthly retention using this dataset?
Data Scientist

ThoughtWorks

Deliveroo Logo

Deliveroo

Mixpanel Logo

Mixpanel

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2 years ago
ML Knowledge
2 years ago
Can you explain the concept of a Neural Network and its operational dynamics?
Data ScientistMachine Learning Engineer

ThoughtWorks

SeatGeek Logo

SeatGeek

Productboard Logo

Productboard

A neural network is a function approximation algorithm inspired by the brain. It is a dense network of nodes, which store values, and edges, which connect nodes. The simplest model is a dense sequential network which has layers of nodes. This network would be called dense when all nodes of one layer are connected to the nodes of the next layer. The network is called sequential because each layer activates one after the other. 


The value of a node is determined by all of the nodes that are connected to it in the previous layers. Each of these values will be multiplied by a weight, and then a bias will be added. This value is passed through an activation function and then result is then the value of the node. 


Typical activation functions are sigmoid, which is shaped like a very wide S, and a relu (rectified linear unit), which is like a hockey stick. The sigmoid activation function is tied to the way that axons in the brain have threshold response functions. 


Neural networks are trained by using the gradient between the output value in the dataset and predicted value. This update is propagated through the network using backpropagation. 


Neural networks are useful because they are universal approximators. This means that an infinitely wide network with one layer input input and output can represent an arbitrary function. This contributes to them being adept at so many tasks.

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2 years ago
Statistics
2 years ago
Would you mind comparing panel data with cross sectional data and tell me the differences?
Data Scientist

ThoughtWorks

Lyft Logo

Lyft

Klarna Logo

Klarna

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2 years ago
Statistics
2 years ago
Do you believe there are any innate properties of a coin that might make it more susceptible to bias?
Data Scientist

ThoughtWorks

Segment Logo

Segment

Curve Logo

Curve

Determining if a coin is biased involves testing whether the coin lands on heads or tails with equal probability. Here's a step-by-step approach to figure out if a coin is biased:

1. Formulate a Hypothesis

  • Null Hypothesis (H0): The coin is fair (i.e., the probability of landing heads is 0.5).
  • Alternative Hypothesis (H1): The coin is biased (i.e., the probability of landing heads is not 0.5).

2. Conduct a Series of Trials

  • Flip the coin a large number of times (e.g., 100, 200, or more). The more trials, the more reliable your results.
  • Record the outcome of each flip (heads or tails).

3. Calculate the Proportion of Heads

  • Count the number of heads HH and the total number of flips NN.
  • Calculate the proportion of heads: p=Number of Heads / Total number of flips

4.Calculate the Z-Score:

  • The Z-score measures how many standard deviations the observed proportion is from the expected proportion.

compate the z score aginst the established confidence level established and pvalue to determine if we can reject the null hypothosis or not

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2 years ago
Statistics
2 years ago
Could you explain how to cleanse a dataset of biases?
Data Scientist

ThoughtWorks

Flexport Logo

Flexport

Yandex Logo

Yandex

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2 years ago

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*All interview questions are submitted by recent ThoughtWorks Data Scientist candidates, labelled and categorized by Prepfully, and then published after being verified by Data Scientists at ThoughtWorks.

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