Data Analytics Interview Questions and Answers

What is Data Analysis?

Ans: Data analysis is the process of understanding and manipulating data to produce meaningful information about a situation. Data analysis aims to improve the quality of your products or services by revealing confidential or otherwise invalid information.

Data analysis can be performed on both physical and digital files, making it suitable for use in both commercial and non-commercial settings. It can also be used in health care, education, government, finance, insurance, and marketing.

Who are the data analysts? What role do they have?

Ans: Data analysts work in data analysis and management to help businesses understand and drive results. They use their technical and business skills to ensure that their clients get the most from their data sources.

Data analysts work with other team members on projects to understand how a company uses its data, what it needs to do to improve its process for analyzing and using data, and how it can improve these processes. They also work on projects involving integrating new technology into existing processes.

Data analysts use a variety of tools, namely spreadsheet software, Sheets, Excel spreadsheets, databases, reports, website analytics tools (such as Google Analytics), social media analysis tools, web development tools, mobile application development tools (like Appcelerator), SEO/social media marketing services (Google Blueprints), content marketing services, etc.

What are the exceptional skills required to be a successful data analyst?

Ans: The term Data Analysts has become a new hot topic. It is one of the most popular job profiles, recognized globally due to its huge salary package. Furthermore, to become a successful data analyst, one must possess the following skills:

• Should be proficient with programming languages like JavaScript, or ETL frameworks, databases like SQL, SQLite, Db2, etc.,
• A data analyst must proficiently examine, handle, collect, and disseminate large amounts of data.
• Must have sufficient technical knowledge of database design, data mining, and segmentation techniques.
• Have in-depth knowledge of the statistical packages for analyzing massive datasets like SAS, Excel, and SPSS.
• Should be proficient in data visualization tools for representation.
• Data cleaning
• High-end Microsoft Excel skills
• Linear Algebra and Calculation

List the responsibilities/job profile of a Data Analyst.

Ans: A data analyst has to perform the below-listed tasks:

• Collect and analyze data from a variety of sources.
• Filter out clean data collected from different sources.
• Offer support for every aspect of data analysis
• Analyze large/complex datasets
• Figure out hidden patterns.
• Keep databases safe.
• Data preparation
• Quality Assurance
• Troubleshooting
• Report generation and preparation

What does “Data Cleansing” mean? What are the best ways to practice this?

Ans: Data cleansing is removing or filtering certain data from an article or report to ensure it is accurate and up-to-date. It can be used in several ways, including correcting errors in content, improving the user experience, and enhancing product functionality. Data cleansing can be performed on an individual or group basis.

Achieve this goal requires the right combination of factors:

• Data quality and quantity management
• Data security and organization structure
• Technical expertise

The best practices for data cleaning include the following:

• Developing a clear purpose for the action.
• establishing goals for progress
• prioritizing work
• managing resources, and
• Managing expectations

List out the best tools used for data analysis.

Ans: The most useful tools for data analysis are:

• Tableau
• Google Fusion Tables
• Google Search Operators
• KNIME
• R Programming
• SAS
• Python
• Jupyter Notebook
• Looker
• Microsoft Power BI
• TIBCO Spotfire
• RapidMiner
• Solver
• OpenRefine
• NodeXL
• Apache Spark
• Google Data Studio
• Domo

What is the difference between data mining and data profiling?

Ans: Data mining is gaining knowledge about a subject by studying and analyzing large amounts of data. Data profiling is the opposite, the process of gaining knowledge about a subject by understanding how data is used in various industries. Data mining improves products or services that can be applied to any industry. In contrast, data profiling is used to understand how specific industries use data in specific ways.

What is “Clustering?” Name the properties of clustering algorithms.

Ans: Clustering can be defined as a process in which data is classified into clusters and groups. A clustering algorithm groups unlabeled items into classes and groups of the same items.

The properties of clustering algorithms are as follows:

Algorithms cluster data points based on their similarity. This improves classification accuracy and reduces false discovery rates (FRS).

Algorithms use mutual exclusion to ensure that only one instance of a clustering algorithm runs at any given time. This ensures that all data points are included in the analysis but does not reduce FRS.

The number of instances of an algorithm depends on several factors, including the size and complexity of the cluster, the type and amount of data involved in the analysis, and whether or not there is an overlap between clusters.

What is the K-mean Algorithm?

Ans: The K-mean algorithm measures the average distance between two events. It measures how close two events are to being by chance, using a technique similar to the Durbin-Scheimn test. The algorithm estimates the most likely outcome of an event based on the amount of k-means data available for that event.

What is Time Series analysis?

Ans: Time series analysis is the scientific study of periodic variations in a set of variables over time. It is a technique used in the physical and life sciences to assess the reliability and validity of measurement systems, model development, and statistical procedures.

 The basic idea behind time series analysis is to identify changes over time in a related variable but not necessarily a causative variable. The sample size required for analysis can be determined by how many observations are needed for each component to have a certain level of significance (e.g., p-threshold). The sample size can also be determined by how many samples will need to be taken from each component before evidence of a significant relationship between the variables.

What is the difference between Overfitting and Underfitting?

Ans: There are two types of underfitting: Overfitting and Underfitting. Overfitting is the process by which a model is fitted to a dataset with features that are not significantly different from one another. At the same time, underfitting is the process by which a model is fitted to a dataset with significantly different features.

What are the different types of Hypothesis testing?

Ans: Hypothesis testing is a type of research that involves testing a hypothesis to see if it’s true or not. This type of research aims to discover if there’s any truth to the hypothesis being tested. There are two main types of hypothesis testing: single-variable and multivariable.

A Single-variable test uses one variable to test the other variable. A multivariate test uses multiple variables in addition to the single variable, such as demographics, education level, and job experience.

What is the difference between COUNT, COUNTA, COUNTBLANK, and COUNTIF in Excel?

Ans: Go through the below-shared points to know the difference between COUNT, COUNTA, COUNTBLANK, and COUNTIF in Excel.

• COUNT function: It returns the count of numeric cells in a range.
• COUNTA function: It counts the non-blank cells in a range.
• COUNTBLANK function: It gives the count of blank cells in a range.
• COUNTIF function: It returns the count of values by checking a given condition.

How do you make a dropdown list in MS Excel?

Ans: Follow the below-shared steps to make a dropdown list in MS Excel:

• Click on the Data tab, present in the ribbon.
• Under the Data Tools group, click on Data Validation.
• Then navigate to Settings > Allow > List.
• Choose the source you want to provide as a list array.

What is the difference between a WHERE clause and a HAVING clause in SQL?

Ans:

WHERE

HAVING

WHERE clause operates on row data.

The HAVING clause operates on aggregated data.

In the WHERE clause, the filter occurs before any groupings are made.

HAVING is used to filter values from a group.

Aggregate functions are not applicable.

Aggregate functions are applicable.

Syntax of WHERE clause:

SELECT column1, column2, …

FROM table_name

WHERE condition;

Syntax of HAVING clause;

SELECT column_name(s)

FROM table_name

WHERE condition

GROUP BY column_name(s)

HAVING condition

ORDER BY column_name(s);

What is the meaning of LOD in Tableau?

Ans: In Tableau, LODs are applied to the data in a way that preserves the integrity of the data. For example, if you have a table with two columns and LODs applied to one column, this will preserve the integrity of the data.

LODs are applied to the data to preserve the integrity of both columns. This means that if you have two separate tables with two different types of fields, then both columns will be preserved. If you have three tables with all different types of fields, then only one column will be preserved.

What are the different joins that Tableau provides?

Ans: Joins in Tableau are almost similar to the SQL join statement. Below are some types of joins that Tableau supports. Have a look at them:

• Left Outer Join
• Right Outer Join
• Full Outer Join
• Inner Join

What is a Gantt chart in Tableau?

Ans: A Gantt chart is a graphical representation of tasks that need to be completed for them to be added to the To-do list. It can be used to track progress and keep track of tasks that still need to be completed. A Gantt chart can help you keep track of your work, resources, and schedule. It gives you an overview of the status of all your tasks, so you can see what’s left to do and where the next step is. It also lets you know how much time remains until the task is completed or done so that you can plan.

Gantt Charts are useful because they allow you to track everything from beginning to end without thinking about it all at once. They’re also great for users to stay up-to-date on their work because they’ll always have something new coming out.

What is Data Validation?

Ans: Data validation is a process that helps ensure that the data you are collecting is accurate and up-to-date. It involves checking the data against known and accepted standards to ensure high quality. Data validation can be applied to any record, from simple ones such as an address or phone number to more complex ones such as credit card or bank account information.

Data validation can also be performed on files and objects in C# or Java used for validation purposes. The first thing you need to do is create a validating resource for your application. This will contain all the information you need to check the validity of your records against known standards (e.g., reliability, completeness, etc.). You can also create custom resources if needed (see The Custom Resource). Once your validating resource has been created, it’s time to check all the data against these standards.

What is the use of a Pivot table?

Ans: A Pivot table is a data table that shows the changes in a series of rows over time. A pivot table is useful when you need to make changes to your data but want to use only some of the dataset.

A pivot table can display all of your items in a single row or multiple rows, depending on your needs. As you make changes, the new rows are added to the top of the pivot table.

What is Hierarchical Clustering?

Ans: Hierarchical clustering (HAC) is a type of data quality monitoring that uses a process of repeated groupings to improve the reliability and accuracy of your data.

A Hierarchical Clustering (HAC) algorithm can be used to improve the accuracy and reliability of your data. It involves using multiple groups of observations to improve your dataset’s overall quality and stability.

What steps are involved when working on a data analysis project?

Many steps are involved when working end-to-end on a data analysis project. Here I present to you some of the important steps as mentioned below:

• Modeling
• Data validation
• Implementation
• Problem statement
• Data cleaning and preprocessing
• Data exploration
• Verification

What is Time Series Analysis?

Ans: Time series analysis is a statistical technique that uses time-series data to assess the connection between two or more variables. Time-series analysis can be used to:

• Determine the reliability of a test statistic
• Determines whether there is a significant relationship between two or more variables
• Determine if there is an association between two or more variables and physical activity
• Determine if there is an interaction between two or more variables and physical activity

Where can Time Series Analysis be used?

Ans: Time Series Analysis (TSA) can be used in multiple domains and has a vast range of usage. Some of the places where TSA plays an important role are shared below:

• Statistics
• Signal processing
• Astronomy
• Applied science
• Econometrics
• Weather forecasting
• Earthquake prediction

What is Collaborative Filtering?

Ans: Collaborative filtering is a technology that uses multiple parties to ensure that data is collected and stored in a way that is accurate and up-to-date. It can be used in personal and commercial settings so that it can be used for any data collection.

Collaborative filtering involves two or more parties working together to ensure that data is collected and stored in a way that is accurate and up-to-date. The first party works with the second party on the collaboration, so they can work out how to best achieve the collaboration goals. They may also work together on specific tasks, such as generating reports or updating files.

Collaborative filtering allows you to:

• Ensure that all of your data is being collected by your privacy rules
• Enforce policies on what information you are allowed to collect from each party
• Prevent disagreements between parties.
• Monitor progress toward achieving your goals

What is the K-means algorithm?

Ans: K-means algorithm is a technique used to monitor the performance of a system by assigning each node to one or more other nodes in the system. Each node uses K-means algorithms to find clusters of data points that are close together and contain similar patterns.

The algorithm assigns each cluster a unique k value, representing its similarity with all the other clusters.

What is the difference between Principal Component Analysis (PCA) and Factor Analysis (FA)?

Ans: The difference between Principal Component Analysis (PCA) and Factor Analysis (FA) is that PCA is more accurate for analyzing large data sets, whereas FA is more accurate for analyzing small data sets.

Principal components are used in PCA to represent individual traits and factors, while factor variables are used in FA to represent individual traits and factors. The principal component analysis (PCA) technique uses two or more principal components to produce an overall principal component diagram representing the data’s structure. The factor analysis technique uses one or more common factors to produce an overall factor-analyzed principal component diagram that represents the structure of the data.

What are the different challenges one faces during data analysis?

Ans: There are many challenges one faces during data analysis. Some of the things you will face while analyzing data include the following:

Data quality: It is important to ensure that your analysis is accurate and up-to-date. You should always check your results regularly and update them if necessary.

Time management: It is important to manage your time well so that you can focus on your analysis instead of doing other tasks. This way, you can ensure that the analysis is done on time and in the right format. Consider setting a timer for your work session to stay focused on the task without being distracted by other activities in the room or world around you.

Ensuring accuracy: It is important to ensure that all of your data points are correct before starting an analysis session so that it does not lead to errors during processing later on down the road when results need to be shared with stakeholders or clients who might be interested in further investigation into a given dataset or study topic based on their own needs and requirements (i.e., client’s needs).

Explain Normal Distribution.

They are an important part of statistical inference because they allow us to infer the likelihoods and proportions associated with various data points.

A normal distribution is a probability distribution with a certain percentage of the variance explained by the standard deviation. The idea behind normal distribution is that there should be a certain amount of randomness in the data, so it should be possible to make inferences about the likelihood of events based on this amount of randomness. Normal distributions are used in statistics to represent probabilities and also in probability theory to represent probabilities.

What do you mean by data visualization?

Ans: Data visualization is a form of storytelling that takes data and visualizes it in a way that makes sense to the audience. Data visualization shows how data can be used to make sense of data. It uses images, sound, and other elements to make the information more clear and understandable. Data visualization can be used for many different purposes, such as explaining processes or helping people understand them.

It can also be used to convey information about a business or project. This section will explain some of the types of data visualizations that you may find in your work area.

List some Python libraries that are used in data analysis.

Ans: Several Python libraries that can be used for data analysis include:

• NumPy
• SciPy
• SciKit
• Bokeh
• Matplotlib
• Pandas

Explain a hash table.

Ans: A hash table is a memory management system that stores and manages data using cryptographic techniques. It is an efficient and secure way to store and retrieve large amounts of data. A hash table is a memory management system that uses the SHA-256 algorithm to protect the data against theft or damage.

Brief disadvantages of data analysis

Ans: There are many disadvantages to data analysis. It consumes time and energy. Data analysis requires a lot of time and energy to process so that it can be used for other purposes, such as research or project management. Since it is time-consuming, it is not generally used by the fastest-growing companies, in which there is a need for speed and accuracy in their data analyses.

What do you mean by univariate, bivariate, and multivariate analysis?

Ans: Univariate analysis: Univariate analysis is the first step in finding a treatment or disease that will work well for your circumstances. You can use univariate analysis to determine if a treatment or disease will help you lose weight, improve your health, or get better results in any of your studies.

Bivariate analysis is the second step in finding a treatment or disease that will work well for you. Bivariate analysis can determine whether a treatment works best on one group of people and not another, how well it works on one test compared to another, and how well it works over time.

Multivariate analysis is the third step in finding a treatment or disease that will work best for you. You can use multivariable analyses to find out how well a therapy works on one variable and not another, how well it does on another task, and how much this therapy helps you lose weight compared to no therapy.

What do you mean by logistic regression?

Ans: Logistic regression is a mixed model that uses the logistic curve to predict the likelihood of a particular event. The likelihood of an event is determined by taking the product of two or more slopes and then dividing it by the standard error.

Describe N-gram in detail.

Ans: The N-gram is a type of language pattern that represents the total number of times an item occurs in a language. It is used to detect similarities and differences between languages.

An “n-gram” consists of two or more words representing the total number of times an item appears in a particular language. The word “n” indicates the number of times the item appears in that language. For example, if you want to learn how many words are in a certain sentence, you would use “n-1”. If you want to learn how many phrases are in a sentence, you will use “n + 1”.

Dissimilarities between a data lake and a data warehouse?

Ans: Dissimilarities between a data lake and a data warehouse are discussed below:

Data Lakes: Data lakes are data warehouses that support the storage and retrieval of data and the management of data. Data lakes are a database with two important differences from other types: They support online and offline access to the data, making them ideal for use in retail and commercial environments.

Data Warehouse is a centralized repository where data from operational systems and other sources is stored. It is a standard tool for integrating data across teams or departments in mid-to-large-sized organizations. Data warehouses can be of the following types:

• Enterprise data warehouse (EDW): An EDW helps the entire organization make decisions.
• Operational Data Store (ODS): The ODS has functionality like reporting sales or employee data.

Differentiate between variance and covariance.

Ans: Variance is the difference between a data set’s mean and variance. Variance measures how much variation there is within a data set. Covariance is the amount of overlap between two or more independent variables in a data set that has no significant relationship with each other.

In data analysis, how do you define an outlier?

Ans: An outlier is a term used in data analysis to refer to a deviation from an expected value representing the difference between two values, expressed as an error. It measures how skewed the data is and can be used in statistical analysis to identify sources of bias.

What Is Metadata?

Ans: Metadata is information that is not just there but also adds to the overall experience of a website. It can be anything from website code, images, or text that identifies the page you are on as being your content. The most common type of metadata is code, which can be found in websites’ file names and structures. 

Code can also be found in the site’s directory structure and files. There are various ways to add metadata to websites: You can add it directly to the file using command-line tools such as wget or git b.

How Many Types of Visualizations?

Ans: Many different types of visualizations can be created, each with its strengths and weaknesses. A good starting point is to look at the most common visualization types and how they work.

You can then create your customized visualizations using these basic guidelines.

• Bar Visualization: This is the most basic type of visualization, in which you display a set amount of data in a bar chart or graph. This type of visualization is useful for tracking changes over time and exploring new research areas.
• Scatter Visualization: This is a variation on the bar visualization, in which you display a series of points or dots over time. The dots may be solid or colored to show different values over time. These types of visualizations are useful for tracking changes across multiple variables, such as variables that change over time (e.g., growth rate), variables that change only at certain points in time (e.g., sample size), and variables based on categorical characteristics (e.g., gender).
• Charts 
• Column charts
• Heat maps
• Line graphs
• Bullet graphs
• Waterfall charts

What Is Data Wrangling?

Ans: Data wrangling reduces the volume of data you have by collecting and analyzing new, useful information that you can use to improve your research.

Data wrangling can be done online or in person. Online data wrangling may include using a website like Google Analytics to track and analyze the usage of your website. In-person data wrangling may include meeting with potential clients or customers, making introductions, and preparing slides for presentations.

The goal of data wrangling is to reduce the amount of data you have on file while increasing the amount you have on hand to conduct more effective research. This will help ensure a high-quality product and service for your client and avoid costly errors later.

What is Logistic Regression?

Ans: Logistic regression is a type of mixed model that combines two or more of the following features:

• A logistic curve, which shows how much of a treatment effect should be expected based on the odds ratio (OR),
• A lagged regression, which shows how much of an effect should be expected based on the value (L) and slope (S) of the lagged curve
• A censored logistic regression shows how much of an effect should be expected if no information about participants’ status and health conditions in a study group has been collected.

What Is Linear Regression?

Ans: Linear regression is a type of multivariate regression that uses only one or two measures of your data to test the relationship between two variables. It was developed by psychologist Robert J. Shiller and is used in many industries, including finance, health care, and retail.

Linear regression tests the relationship between two variables using Duncan’s multiple R2 tests. In other words, it compares the mean of each variable with the mean of all the other variables in the model to see if there is a significant difference.

Is Version Control Important? Define and explain.

Ans: Version control systems (VCS) are distributed systems that allow you to keep track of different versions of your software and data. They allow you to share changes between different projects and make them available to all the users who are part of the project. There are several types of version control systems, each with its advantages and disadvantages.

The basic version control system is a repository where two or more people can store files representing changes to an application’s codebase. The repository contains both files (.js and .jsx) and directories (.config and .configure).

A source code management system (SCMS) is a different version control system. SCMSs provide an environment where developers can work collaboratively on their code while keeping track of its history and revision history. They serve as repositories for developers to upload their source code files, which contain all of the changes required to create new versions of their software without first editing any existing ones.

What is KPI?

Ans: KPI stands for Key Performance Indicator. It is a measurement of the success of a company or product in achieving a specific goal. It can be used to measure the progress made by an organization, and it can be used to identify areas where improvement is needed. A KPI is often used as a way of tracking the progress made by an organization, and it can also be used to identify areas that need improvement.

What is Map Reduce?

Ans: MapReduce is a software framework for developing and consuming web services that support distributed systems. It combines the advantages of distributed systems with the flexibility of software development to provide a powerful tool for creating and deploying websites.

Why was Map Reduce designed for?

Ans: MapReduce was designed to support the development of high-fidelity, high-volume, real-time web services. Its flexible architecture enables developers to create websites with various features, from simple pages to complex applications with interactive elements and data sources.

What is exploratory data analysis?

Ans: Exploratory data analysis is a type of statistical test that takes a sample of data and looks for patterns in the data that may indicate an issue or problem with the sample. The most common use of exploratory analysis is to look for reasons why the samples were not statistically significant. This can be done by conducting multiple analyses or more detailed statistical tests.

To use exploratory analysis, you need to have some basic information about your study:

• What is your study about?
• What do you want to find out?
• How much do you want to examine?
• What are the main findings from your study?
• How can you improve your results?

Is Python the best language for data analysis? Explain.

Ans: Python is a fast and easy-to-learn programming language perfect for data analysis and statistics. It has a well-defined language that makes it easy to learn and great for data analysis.

It features an object-oriented style, which makes it easy to understand and make changes to your code. Python has many built-in functions such as read line, string concatenation, math operations like sin or cos, string parsing, text formatting, image processing, file writing, etc.

The Data Analyst job profile is the new hot topic, recognized globally. Pursuing your career in data analytics is the best decision. Even the big bull of the Information & Technology Industry encourages and says that the future IT industry will revolve around data analysts. So, if you wish to be a successful data analyst and land your dream job, connect with ProIT Academy.

ProIT Academy provides the best Data Analytics training in Pune with sessions led by the smartest minds in the industry. It also offers interviews and workshops on various topics to help you learn about new technologies. We’ve curated a list of the most important data analytics interview questions and answers. So, without delay, go through all the data analytics interview questions and land your dream job at your company!!