HCL Technologies Data Science Recently Asked Interview Questions Answers
What are Recommender Systems?
Recommender systems are a subclass of information filtering systems that are meant to predict the preferences or ratings that a user would give to a product.
Explain cross-validation.?
It is a model validation technique for evaluating how the outcomes of a statistical analysis will generalize to an independent data set. It is mainly used in backgrounds where the objective is forecast and one wants to estimate how accurately a model will accomplish in practice. The goal of cross-validation is to term a data set to test the model in the training phase (i.e. validation data set) in order to limit problems like overfitting and gain insight on how the model will generalize to an independent data set.
What is Collaborative Filtering?
The process of filtering used by most recommender systems to find patterns and information by collaborating perspectives, numerous data sources, and several agents.
Do gradient descent methods at all times converge to a similar point?
No, they do not because in some cases they reach a local minima or a local optima point. You would not reach the global optima point. This is governed by the data and the starting conditions.
What is the goal of A/B Testing?
This is a statistical hypothesis testing for randomized experiments with two variables, A and B. The objective of A/B testing is to detect any changes to a web page to maximize or increase the outcome of a strategy.
What are the drawbacks of the linear model?
Some drawbacks of the linear model are:
The assumption of linearity of the errors.
It can’t be used for count outcomes or binary outcomes
There are overfitting problems that it can’t solve
What is the Law of Large Numbers?
It is a theorem that describes the result of performing the same experiment a large number of times. This theorem forms the basis of frequency-style thinking. It says that the sample mean, the sample variance and the sample standard deviation converge to what they are trying to estimate.
What are confounding variables?
These are extraneous variables in a statistical model that correlate directly or inversely with both the dependent and the independent variable. The estimate fails to account for the confounding factor.
In a class of 30 students, approximately what is the probability that two of the students have their birthday on the same day (defined by same day and month) (assuming it’s not a leap year)?
For example – Students with birthday 3rd Jan 1993 and 3rd Jan 1994 would be a favorable event.
A) 49%
B) 52%
C) 70%
D) 35%
Ans: (C)
The total number of combinations possible for no two persons to have the same birthday in a class of 30 is 30 * (30-1)/2 = 435.
Now, there are 365 days in a year (assuming it’s not a leap year). Thus, the probability of people having a different birthday would be 364/365. Now there are 870 combinations possible. Thus, the probability that no two people have the same birthday is (364/365)^435 = 0.303.
Thus, the probability that two people would have their birthdays on the same date would be 1 – 0.303 = 0.696
Ahmed is playing a lottery game where he must pick 2 numbers from 0 to 9 followed by an English alphabet (from 26-letters). He may choose the same number both times.
If his ticket matches the 2 numbers and 1 letter drawn in order, he wins the grand prize and receives $10405. If just his letter matches but one or both of the numbers do not match, he wins $100. Under any other circumstance, he wins nothing. The game costs him $5 to play. Suppose he has chosen 04R to play.
What does P-value signify about the statistical data?
P-value is used to determine the significance of results after a hypothesis test in statistics. P-value helps the readers to draw conclusions and is always between 0 and 1.
• P- Value > 0.05 denotes weak evidence against the null hypothesis which means the null hypothesis cannot be rejected.
• P-value <= 0.05 denotes strong evidence against the null hypothesis which means the null hypothesis can be rejected.
• P-value=0.05is the marginal value indicating it is possible to go either way.
If you dealt 13 cards, what is the probability that the 13th card is a King?
A) 1/52
B) 1/13
C) 1/26
D) 1/12
Ans: (B)
Since we are not told anything about the first 12 cards that are dealt, the probability that the 13th card dealt is a King, is the same as the probability that the first card dealt, or in fact any particular card dealt is a King, and this equals: 4/52
A fair six-sided die is rolled 6 times. What is the probability of getting all outcomes as unique?
A) 0.01543
B) 0.01993
C) 0.23148
D) 0.03333
Ans: (A)
For all the outcomes to be unique, we have 6 choices for the first turn, 5 for the second turn, 4 for the third turn and so on
Therefore the probability if getting all unique outcomes will be equal to 0.01543
What are Recommender Systems?
Recommender systems are a subclass of information filtering systems that are meant to predict the preferences or ratings that a user would give to a product.
Explain cross-validation.?
It is a model validation technique for evaluating how the outcomes of a statistical analysis will generalize to an independent data set. It is mainly used in backgrounds where the objective is forecast and one wants to estimate how accurately a model will accomplish in practice. The goal of cross-validation is to term a data set to test the model in the training phase (i.e. validation data set) in order to limit problems like overfitting and gain insight on how the model will generalize to an independent data set.
What is Collaborative Filtering?
The process of filtering used by most recommender systems to find patterns and information by collaborating perspectives, numerous data sources, and several agents.
Do gradient descent methods at all times converge to a similar point?
No, they do not because in some cases they reach a local minima or a local optima point. You would not reach the global optima point. This is governed by the data and the starting conditions.
What is the goal of A/B Testing?
This is a statistical hypothesis testing for randomized experiments with two variables, A and B. The objective of A/B testing is to detect any changes to a web page to maximize or increase the outcome of a strategy.
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| HCL Technologies Data Science Recently Asked Interview Questions Answers |
What are the drawbacks of the linear model?
Some drawbacks of the linear model are:
The assumption of linearity of the errors.
It can’t be used for count outcomes or binary outcomes
There are overfitting problems that it can’t solve
What is the Law of Large Numbers?
It is a theorem that describes the result of performing the same experiment a large number of times. This theorem forms the basis of frequency-style thinking. It says that the sample mean, the sample variance and the sample standard deviation converge to what they are trying to estimate.
What are confounding variables?
These are extraneous variables in a statistical model that correlate directly or inversely with both the dependent and the independent variable. The estimate fails to account for the confounding factor.
In a class of 30 students, approximately what is the probability that two of the students have their birthday on the same day (defined by same day and month) (assuming it’s not a leap year)?
For example – Students with birthday 3rd Jan 1993 and 3rd Jan 1994 would be a favorable event.
A) 49%
B) 52%
C) 70%
D) 35%
Ans: (C)
The total number of combinations possible for no two persons to have the same birthday in a class of 30 is 30 * (30-1)/2 = 435.
Now, there are 365 days in a year (assuming it’s not a leap year). Thus, the probability of people having a different birthday would be 364/365. Now there are 870 combinations possible. Thus, the probability that no two people have the same birthday is (364/365)^435 = 0.303.
Thus, the probability that two people would have their birthdays on the same date would be 1 – 0.303 = 0.696
Ahmed is playing a lottery game where he must pick 2 numbers from 0 to 9 followed by an English alphabet (from 26-letters). He may choose the same number both times.
If his ticket matches the 2 numbers and 1 letter drawn in order, he wins the grand prize and receives $10405. If just his letter matches but one or both of the numbers do not match, he wins $100. Under any other circumstance, he wins nothing. The game costs him $5 to play. Suppose he has chosen 04R to play.
What does P-value signify about the statistical data?
P-value is used to determine the significance of results after a hypothesis test in statistics. P-value helps the readers to draw conclusions and is always between 0 and 1.
• P- Value > 0.05 denotes weak evidence against the null hypothesis which means the null hypothesis cannot be rejected.
• P-value <= 0.05 denotes strong evidence against the null hypothesis which means the null hypothesis can be rejected.
• P-value=0.05is the marginal value indicating it is possible to go either way.
If you dealt 13 cards, what is the probability that the 13th card is a King?
A) 1/52
B) 1/13
C) 1/26
D) 1/12
Ans: (B)
Since we are not told anything about the first 12 cards that are dealt, the probability that the 13th card dealt is a King, is the same as the probability that the first card dealt, or in fact any particular card dealt is a King, and this equals: 4/52
A fair six-sided die is rolled 6 times. What is the probability of getting all outcomes as unique?
A) 0.01543
B) 0.01993
C) 0.23148
D) 0.03333
Ans: (A)
For all the outcomes to be unique, we have 6 choices for the first turn, 5 for the second turn, 4 for the third turn and so on
Therefore the probability if getting all unique outcomes will be equal to 0.01543