Data Science Final Exam | 76
Questions with 100% Verified
Answers
What is revision to the mean? - ✔ ✔ Any anomaly will eventually revert back to
the standard outcome
What are the top regression mistakes? - ✔ ✔ Top regression mistakes:
1) using regression to analyse a non linear relationship.
2) correlation does not equal causation
3) reverse causality - statistical association between A and B does not prove that
A causes B. B may cause A.
4) omitted variable bias
5) highly correlated explanatory variables (multicollinearity)
5) extrapolating beyond the data.
,True or false, the probability that two events will both occur can never be
greater than the probability that each will occur individually - ✔ ✔ True
What is pearson's chi squared test? - ✔ ✔ A statistical test applied to sets of
categorical data to evaluate how likely it is that any observed difference
between the sets arose by chance. It is suitable for unpaired data from large
samples. Use the chi-square test for independence to determine whether there
is a significant relationship between two categorical Variables.
What is the Law of compounding probabilities - ✔ ✔ - if two possible events A
and B are independent then the probability that both A and B will occur is equal
to the product of the individual probabilities (prob(A)*prob(B))
True or false, Last law - if an event can have a number of different and distinct
possible outcomes (A, B, C, etc. ) then the probability that either A or B will
occur is equal to the sum of the individual probabilities of A and B. The sum of all
probabilities of all possible outcomes is 1. - ✔ ✔ True
What is a random variable? - ✔ ✔ Random variable is a function from
sample space that maps to the real line. Think of it as a numerical
"summary" as an aspect of an experiment.
What is a qqplot? - ✔ ✔ a plot to visualize how close a sample distribution is to
a normal distribution
What is Cramer's V Chi Squared Correlation? - ✔ ✔ Correlation of 0 means two
variables are not related, correlation of 1 means they are strongly related
, What is Analysis of Variance (ANOVA) ? - ✔ ✔ Analysis of Variance (ANOVA) -
assess whether the average of a numerical variable for more than two
categories of a categorical variable are statistically different from each other (P
value less than 0.05 means variables are correlated)
How to transform skewed distributions into symmetric? - ✔ ✔ Transform skewed
distributions into Symmetric (since many models are based on assumption of
normality, like Neural Network). For right skewed distribution, take square/cube
root or logarithm of variable. Square root and log can't handle negative numbers.
For left skewed distribution, take square/cube or exponential of variables.
What is ACID in relational databases? - ✔ ✔ Atomicity - requires that each
transaction is "all or nothing", if one part of transaction fails, entire transaction
fails and database state is let unchanged.
Consistency property ensures that any transaction will bring the database
from one valid state to another.
Isolation property ensures that the concurrent execution of transactions results
in a system state that would be obtained if transactions were executed serially.
Durability means that once a transaction has been committed, it will remain
so (even in the event of power loss, crashes or errors)
What is Consistency Availability and Partition Tolerance theorem? -
✔ ✔ Consistency Availability and Partition Tolerance (CAP) theorem states
that there are 3 essential system requirements necessary for successful
design/deployment/implementation of applications in distributed systems:
Distributed system can only guarantee two of these features, not all 3.
Typically Consistency suffers in new large-scale distributed non-relational systems
so ACID collapses. SQL databases only designed to store/manage structured data.
Questions with 100% Verified
Answers
What is revision to the mean? - ✔ ✔ Any anomaly will eventually revert back to
the standard outcome
What are the top regression mistakes? - ✔ ✔ Top regression mistakes:
1) using regression to analyse a non linear relationship.
2) correlation does not equal causation
3) reverse causality - statistical association between A and B does not prove that
A causes B. B may cause A.
4) omitted variable bias
5) highly correlated explanatory variables (multicollinearity)
5) extrapolating beyond the data.
,True or false, the probability that two events will both occur can never be
greater than the probability that each will occur individually - ✔ ✔ True
What is pearson's chi squared test? - ✔ ✔ A statistical test applied to sets of
categorical data to evaluate how likely it is that any observed difference
between the sets arose by chance. It is suitable for unpaired data from large
samples. Use the chi-square test for independence to determine whether there
is a significant relationship between two categorical Variables.
What is the Law of compounding probabilities - ✔ ✔ - if two possible events A
and B are independent then the probability that both A and B will occur is equal
to the product of the individual probabilities (prob(A)*prob(B))
True or false, Last law - if an event can have a number of different and distinct
possible outcomes (A, B, C, etc. ) then the probability that either A or B will
occur is equal to the sum of the individual probabilities of A and B. The sum of all
probabilities of all possible outcomes is 1. - ✔ ✔ True
What is a random variable? - ✔ ✔ Random variable is a function from
sample space that maps to the real line. Think of it as a numerical
"summary" as an aspect of an experiment.
What is a qqplot? - ✔ ✔ a plot to visualize how close a sample distribution is to
a normal distribution
What is Cramer's V Chi Squared Correlation? - ✔ ✔ Correlation of 0 means two
variables are not related, correlation of 1 means they are strongly related
, What is Analysis of Variance (ANOVA) ? - ✔ ✔ Analysis of Variance (ANOVA) -
assess whether the average of a numerical variable for more than two
categories of a categorical variable are statistically different from each other (P
value less than 0.05 means variables are correlated)
How to transform skewed distributions into symmetric? - ✔ ✔ Transform skewed
distributions into Symmetric (since many models are based on assumption of
normality, like Neural Network). For right skewed distribution, take square/cube
root or logarithm of variable. Square root and log can't handle negative numbers.
For left skewed distribution, take square/cube or exponential of variables.
What is ACID in relational databases? - ✔ ✔ Atomicity - requires that each
transaction is "all or nothing", if one part of transaction fails, entire transaction
fails and database state is let unchanged.
Consistency property ensures that any transaction will bring the database
from one valid state to another.
Isolation property ensures that the concurrent execution of transactions results
in a system state that would be obtained if transactions were executed serially.
Durability means that once a transaction has been committed, it will remain
so (even in the event of power loss, crashes or errors)
What is Consistency Availability and Partition Tolerance theorem? -
✔ ✔ Consistency Availability and Partition Tolerance (CAP) theorem states
that there are 3 essential system requirements necessary for successful
design/deployment/implementation of applications in distributed systems:
Distributed system can only guarantee two of these features, not all 3.
Typically Consistency suffers in new large-scale distributed non-relational systems
so ACID collapses. SQL databases only designed to store/manage structured data.
