Data Science Interview Questions and Answers
Question - 101 : - What if instead of finding the best split, we randomly select a few splits and just select the best from them. Will it work?
Answer - 101 : - The decision tree is based on a greedy approach. It selects the best option for each branching. If we randomly select the best split from average splits, it would give us a locally best solution and not the best solution producing sub-par and sub-optimal results.
Question - 102 : - What is a Box-Cox Transformation?
Answer - 102 : - A Box Cox transformation is a way to normalise variables. Normality is an important assumption for many statistical techniques; if your data isn’t normal, applying a Box-Cox means that you are able to run a broader number of tests.
Question - 103 : - What is root cause analysis?
Answer - 103 : - Root cause analysis is the process of tracing back of occurrence of an event and the factors which lead to it. It’s generally done when a software malfunctions. In data science, root cause analysis helps businesses understand the semantics behind certain outcomes.
Question - 104 : - What is the default missing value marker in pandas, and how can you detect all missing values in a DataFrame?
Answer - 104 : - NaN is the missing values marker in pandas. All rows with missing values can be detected by is_null() function in pandas.
Question - 105 : - What is the hyperbolic tree?
Answer - 105 : - A hyperbolic tree or hypertree is an information visualisation and graph drawing method inspired by hyperbolic geometry.
Question - 106 : - What is scientific visualisation? How it is different from other visualisation techniques?
Answer - 106 : - Scientific visualization is representing data graphically as a means of gaining insight from the data. It is also known as visual data analysis. This helps to understand the system that can be studied in ways previously impossible.
Question - 107 : - What are some of the downsides of Visualisation?
Answer - 107 : - Few of the downsides of visualisation are: It gives estimation not accuracy, a different group of the audience may interpret it differently, Improper design can cause confusion.
Question - 108 : - What is the difference between a tree map and heat map?
Answer - 108 : - A heat map is a type of visualisation tool that compares different categories with the help of colours and size. It can be used to compare two different measures. The ‘tree map’ is a chart type that illustrates hierarchical data or part-to-whole relationships.
Question - 109 : - What is disaggregation and aggregation of data?
Answer - 109 : - Aggregation basically is combining multiple rows of data at a single place from low level to a higher level. Disaggregation, on the other hand, is the reverse process i.e breaking the aggregate data to a lower level.
Question - 110 : - What are some common data quality issues when dealing with Big Data?
Answer - 110 : - Some of the major quality issues when dealing with big data are duplicate data, incomplete data, the inconsistent format of data, incorrect data, the volume of data(big data), no proper storage mechanism, etc.