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Write a SQL query to compute a frequency table of a certain attribute involving two joins. What if you want to GROUP or ORDER BY some attribute? What changes would you need to make? How would you account for NULLs?
Lets say the population on Facebook clicks ads with a click-through-rate of P. We select a sample of size N and examine the sample's conversion rate, denoted by hat{P}, what is the minimum sample size N such that Probability( ABS(hat{P} - P) < DELTA ) = 95%. In other words (this is my translation), find the minimum sample size N such that our sample estimate hat{P} is within DELTA of the true click through rate P, with 95% confidence.
Given two binary strings, write a function that adds them. You are not allowed to use any built in string to int conversions or parsing tools. E.g. Given "100" and "111" you should return "1011". What is the time and space complexity of your algorithm?
We have a table called ad_accounts(account_id, date, status). Status can be active/closed/fraud. A) what percent of active accounts are fraud? B) How many accounts became fraud today for the first time? C) What would be the financial impact of letting fraud accounts become active (how would you approach this question)?
What is your biggest stranght? What is your biggest weakness? How do you handle stress?
Which syntax of SQL is used to slice dataset into several chunks
HR manager has asked me: Do you own a house? Are you married? Do you have children and how many? etc. The was no reason for asking these questions. I felt disrespected when i heard them. My enthusiasm for GSK melted like snow is a sunny day. I didnt have anything to hide, but i felt undermined and devalued.
I was asked about the way I would design the "people you may know" application of LinkedIn and about the way I would group "similar" people and jobs with people etc. More or less it was a discussion about collaborative filtering , classification and prediction models (k-means clustering, bayesian model, decision trees ).
What is 19+NULL in SQL
Say the DS team came up with a spam detection algorithm, what metrics would you use to measure success?