Data Analytics & Visualization DAV Viva Questions with answer – sem 6 AI-DS/ML

## Table of Contents DAV Viva Questions

## Module 1: Introduction to Data Analytics and Lifecycle

**Q1: What are the key roles required for a successful analytics project?****A1:** Several key roles are vital for the success of an analytics project. Data scientists are responsible for analyzing data and extracting insights. Data engineers manage data pipelines and infrastructure. Domain experts provide context and understanding of the business domain. Project managers coordinate tasks and resources. Business stakeholders provide guidance and make decisions based on analytics outcomes.

**Q2: Describe the Discovery phase of the Data Analytics Lifecycle.****A2:** The Discovery phase marks the beginning of an analytics project. It involves understanding the business domain, defining the problem, identifying stakeholders, interviewing sponsors, and formulating initial hypotheses. This phase is crucial for setting the direction of the project and establishing a solid foundation for subsequent stages.

**Q3: What activities are involved in the Data Preparation phase?****A3:** The Data Preparation phase focuses on getting the data ready for analysis. This includes setting up the analytic environment, performing data extraction, transformation, and loading (ETL), exploring and understanding the data, cleaning and formatting it, and creating visualizations to gain insights into its characteristics and quality.

**Q4: Explain the Model Planning phase in the Data Analytics Lifecycle.****A4:** The Model Planning phase is where the analytics team decides on the approach to analyze the data. It involves exploring different variables, selecting relevant features, and choosing appropriate models for analysis. This phase lays the groundwork for building predictive or descriptive models that will be used to derive insights from the data.

**Q5: What are the common tools used during the Model Planning phase?****A5:** Common tools for the Model Planning phase include statistical software such as R or Python, along with libraries like scikit-learn or TensorFlow. These tools provide functionalities for data exploration, feature selection, model training, and evaluation, helping analysts in the decision-making process.

**Q6: What activities are encompassed in the Model Building phase?****A6:** The Model Building phase involves implementing the selected models, training them on the prepared data, fine-tuning model parameters for optimal performance, and evaluating their accuracy and effectiveness. This phase requires iterative testing and refinement to ensure the models meet the project objectives.

**Q7: How do you communicate results in the Data Analytics Lifecycle?****A7:** Results are communicated through clear and concise reports, presentations, or visualizations that convey insights derived from the data analysis. Effective communication involves tailoring the message to the audience, highlighting key findings, and providing actionable recommendations based on the analytics outcomes.

**Q8: What is the significance of the Operationalize phase?****A8:** The Operationalize phase is critical for translating analytics insights into actionable outcomes. It involves deploying the developed models into production systems, integrating them with existing workflows, and establishing mechanisms for monitoring model performance and updating them as needed. This phase ensures that analytics solutions deliver value in real-world scenarios.

**Q9: Why is it essential to involve key stakeholders during the Discovery phase?****A9:** Involving key stakeholders during the Discovery phase ensures alignment between analytics objectives and business goals. It helps in gathering relevant domain knowledge, clarifying requirements, and identifying potential challenges early in the project lifecycle. Stakeholder involvement fosters collaboration and ensures that the analytics solution meets the needs of the organization.

**Q10: How does data visualization contribute to the Data Analytics Lifecycle?****A10:** Data visualization plays a crucial role in the Data Analytics Lifecycle by making complex data more accessible and understandable. It helps analysts explore data patterns, identify trends, and communicate insights effectively to stakeholders. Visualization techniques such as charts, graphs, and dashboards facilitate decision-making by providing visual representations of analytical findings.

## Module 2: Regression Models

**Q1: What is simple Linear Regression, and what components does it involve?****A1:** Simple Linear Regression is a statistical method used to model the relationship between a single independent variable and a dependent variable. It involves fitting a regression equation to the data, calculating fitted values and residuals, and minimizing the sum of squared residuals through the method of least squares.

**Q2: How is Multiple Linear Regression different from Simple Linear Regression?****A2:** Multiple Linear Regression extends the concept of Simple Linear Regression to include multiple independent variables in the model. It assesses the relationship between a dependent variable and two or more independent variables, allowing for more complex analyses of the data.

**Q3: What is Logistic Regression, and when is it used?****A3:** Logistic Regression is a statistical method used for modeling the probability of a binary outcome. It is particularly useful when the dependent variable is categorical and has only two possible outcomes, such as “yes” or “no,” “success” or “failure.”

**Q4: Describe the Logistic Response function and its significance in Logistic Regression.****A4:** The Logistic Response function, also known as the sigmoid function, maps the linear combination of predictor variables to the probability of a binary outcome. It ensures that predicted probabilities fall between 0 and 1, making Logistic Regression suitable for modeling probabilities.

**Q5: What are odds ratios, and how are they interpreted in Logistic Regression?****A5:** Odds ratios represent the change in the odds of the outcome occurring for a one-unit change in the predictor variable. In Logistic Regression, they quantify the effect of each predictor on the likelihood of the outcome, providing valuable insights into the relationship between predictors and the outcome variable.

**Q6: What are some similarities and differences between Linear Regression and Logistic Regression?****A6:** Both Linear Regression and Logistic Regression are types of regression models used for predictive modeling. However, Linear Regression models continuous outcomes, while Logistic Regression models binary outcomes. Additionally, the interpretation of coefficients differs between the two models, with Linear Regression focusing on the change in the dependent variable and Logistic Regression focusing on odds ratios.

**Q7: How do you assess the performance of Regression models?****A7:** Regression model performance can be assessed using various metrics such as R-squared (for Linear Regression), accuracy, confusion matrix, and ROC curve (for Logistic Regression). Cross-validation techniques and model selection methods help in choosing the best-performing model.

**Q8: What is Stepwise Regression, and how is it used in model selection?****A8:** Stepwise Regression is a method used for automatic variable selection in regression models. It involves iteratively adding or removing predictor variables based on their contribution to the model’s performance. Stepwise Regression helps in identifying the most relevant variables and improving the model’s predictive accuracy.

**Q9: How do you interpret the coefficients in a Logistic Regression model?****A9:** The coefficients in a Logistic Regression model represent the change in the log odds of the outcome for a one-unit change in the predictor variable. Exponentiating these coefficients gives the odds ratios, which quantify the impact of each predictor on the likelihood of the outcome occurring.

**Q10: What role does Cross-Validation play in assessing Regression models?****A10:** Cross-Validation is a resampling technique used to evaluate the performance of regression models by assessing their generalization ability to unseen data. It helps in estimating the model’s predictive accuracy and identifying potential issues such as overfitting or underfitting. Cross-Validation ensures that the model performs well on new data, beyond the training dataset used for model fitting.

## Module 3: Time Series Analysis

**Q1: What is Time Series Analysis, and why is it important?****A1:** Time Series Analysis is a statistical method used to analyze data collected over time to identify patterns, trends, and seasonality. It is crucial in various fields such as finance, economics, and environmental science for forecasting future values based on historical data.

**Q2: Explain the Box-Jenkins Methodology in Time Series Analysis.****A2:** The Box-Jenkins Methodology, also known as the ARIMA modeling approach, is a systematic framework for modeling and forecasting time series data. It involves three main steps: identification, estimation, and diagnostic checking of the model. This methodology helps in selecting the appropriate ARIMA model to fit the data.

**Q3: What is the Autocorrelation Function (ACF), and how is it used in Time Series Analysis?****A3:** The Autocorrelation Function (ACF) measures the correlation between observations at different time lags within a time series. It helps in identifying patterns of correlation, such as seasonality or trend, and selecting appropriate lag values for autoregressive or moving average models.

**Q4: What are Autoregressive (AR) Models, and how do they work in Time Series Analysis?****A4:** Autoregressive (AR) Models are time series models that use past observations of the variable to predict future values. They assume that the current value of the variable depends linearly on its previous values, with the addition of random error.

**Q5: Describe Moving Average (MA) Models and their role in Time Series Analysis.****A5:** Moving Average (MA) Models are time series models that use past forecast errors to predict future values. They capture the short-term fluctuations in the data by modeling the relationship between the current value and past forecast errors.

**Q6: What is the difference between ARMA and ARIMA Models in Time Series Analysis?****A6:** ARMA (Autoregressive Moving Average) models combine both autoregressive and moving average components to capture the temporal dependencies in the data. ARIMA (Autoregressive Integrated Moving Average) models include an additional differencing step to make the time series stationary before modeling.

**Q7: How do you build and evaluate an ARIMA Model in Time Series Analysis?****A7:** To build an ARIMA Model, you first identify the appropriate order of differencing (d), autoregressive (p), and moving average (q) components using methods like ACF and Partial Autocorrelation Function (PACF) plots. Then, you estimate the parameters and fit the model to the data. Evaluation involves assessing the model’s goodness of fit using diagnostic tests and validating its forecasting performance on holdout data.

**Q8: What are some reasons to choose ARIMA models for Time Series Analysis?****A8:** ARIMA models are suitable for analyzing time series data with trend and seasonality patterns. They provide interpretable parameters and can capture complex temporal dependencies in the data. ARIMA models are widely used for forecasting applications in various fields.

**Q9: What precautions should be taken when using ARIMA models in Time Series Analysis?****A9:** When using ARIMA models, it’s essential to ensure that the time series is stationary or can be made stationary through differencing. Care should be taken to avoid overfitting by selecting appropriate model orders and validating the model’s performance on out-of-sample data. Additionally, outliers and missing values should be handled appropriately before model fitting.

**Q10: How does Time Series Analysis differ from other types of data analysis?****A10:** Time Series Analysis focuses specifically on data collected over time, aiming to understand and forecast temporal patterns and trends. Unlike cross-sectional or panel data analysis, which considers observations at a single point in time, Time Series Analysis accounts for the sequential nature of data and the dependencies between observations.

## Module 4: Text Analytics

**Q1: What is the history of text mining, and how has it evolved over time?****A1:** Text mining, also known as text analytics, has roots dating back to the 1960s with early work in information retrieval and natural language processing. Over time, advancements in computational linguistics, machine learning, and big data technologies have led to the development of more sophisticated text mining techniques capable of extracting insights from unstructured text data.

**Q2: What are the seven practices of text analytics, and how do they contribute to the field?****A2:** The seven practices of text analytics encompass various techniques and methodologies used for extracting meaning from unstructured text data. These practices include text summarization, sentiment analysis, topic modeling, named entity recognition, document categorization, entity linking, and concept extraction. Each practice addresses different aspects of text analysis to derive valuable insights from textual information.

**Q3: What are some application and use cases for text mining?****A3:** Text mining finds applications across diverse domains such as customer feedback analysis, market research, social media monitoring, healthcare informatics, and legal document analysis. Use cases include sentiment analysis of product reviews, summarization of news articles, topic modeling of research papers, and categorization of customer support tickets.

**Q4: Describe the steps involved in text analysis.****A4:** Text analysis typically involves several steps, including collecting raw text data, preprocessing and cleaning the text, representing the text in a suitable format (e.g., bag-of-words or word embeddings), applying text mining techniques such as TF-IDF or topic modeling, and interpreting the results to gain insights.

**Q5: Can you provide an example of text analysis?****A5:** Sure! Let’s consider the task of sentiment analysis on customer reviews of a product. We collect raw text data from online review platforms, preprocess the text by removing stopwords and punctuation, represent the text using TF-IDF vectors, and classify each review as positive, negative, or neutral based on sentiment analysis algorithms. Finally, we analyze the distribution of sentiments to understand customer opinions about the product.

**Q6: What is Term Frequencyâ€”Inverse Document Frequency (TF-IDF), and how is it used in text mining?****A6:** Term Frequencyâ€”Inverse Document Frequency (TF-IDF) is a numerical statistic that reflects the importance of a term in a document relative to a collection of documents. It is calculated by multiplying the term frequency (how often a term appears in a document) by the inverse document frequency (how rare the term is across all documents). TF-IDF is commonly used for text representation and feature weighting in text mining tasks.

**Q7: How do text analytics techniques like sentiment analysis and topic modeling help in gaining insights from textual data?****A7:** Sentiment analysis helps in understanding the emotional tone of text data, enabling businesses to gauge customer opinions, identify trends, and address issues proactively. Topic modeling, on the other hand, organizes textual data into coherent topics or themes, allowing analysts to uncover hidden patterns, explore relationships, and extract actionable insights from large text collections.

## Module 5: Data Analytics and Visualization with R

**Q1: How can you import and export data in R?****A1:** In R, you can import data from external sources using functions like `read.csv()`

for CSV files, `read.table()`

for tabular data, and `readRDS()`

for R data files. Similarly, data can be exported using functions like `write.csv()`

and `write.table()`

.

```
# Example of importing a CSV file
data <- read.csv("data.csv")
# Example of exporting data to a CSV file
write.csv(data, "exported_data.csv")
```

**Q2: What are some common data types and attributes in R?****A2:** Common data types in R include numeric, character, logical, integer, and factor. Attributes such as names, dimensions, and class define additional properties of objects in R.

```
# Example of defining a numeric vector
numeric_vector <- c(1.5, 2.3, 3.7)
# Example of defining a character vector
character_vector <- c("apple", "banana", "orange")
```

**Q3: How can descriptive statistics be computed in R?****A3:** Descriptive statistics such as mean, median, standard deviation, and quartiles can be computed in R using functions like `mean()`

, `median()`

, `sd()`

, and `quantile()`

.

```
# Example of computing mean and standard deviation
mean_value <- mean(numeric_vector)
sd_value <- sd(numeric_vector)
```

**Q4: What is the importance of visualization in exploratory data analysis (EDA)?****A4:** Visualization is crucial in EDA as it helps in understanding the structure of the data, identifying patterns, trends, and outliers. It provides insights that may not be apparent from numerical summaries alone.

```
# Example of visualizing a histogram of a numeric variable
hist(numeric_vector)
```

**Q5: How can you visualize single variables in R?****A5:** Single variables can be visualized in R using histograms, boxplots, bar plots, density plots, and scatter plots, among others.

```
# Example of visualizing a histogram of a numeric variable
hist(numeric_vector)
```

**Q6: What techniques are used for examining multiple variables in R?****A6:** Techniques for examining multiple variables in R include scatter plots, pairs plots, heatmaps, and correlation matrices.

```
# Example of creating a scatter plot matrix
pairs(iris[, 1:4])
```

**Q7: What is the difference between data exploration and presentation in R?****A7:** Data exploration in R involves understanding the structure and patterns in the data using various visualization and statistical techniques. Presentation, on the other hand, focuses on creating visually appealing and informative plots or reports to communicate the findings effectively.

```
# Example of data exploration with a scatter plot
plot(data$X, data$Y)
```

## Module 6: Data Analytics and Visualization with Python

**Q1: What are the essential data libraries for data analytics in Python?****A1:** Essential data libraries for data analytics in Python include Pandas for data manipulation and analysis, NumPy for numerical computing, and SciPy for scientific computing and statistical analysis.

```
# Example of importing Pandas, NumPy, and SciPy
import pandas as pd
import numpy as np
import scipy
```

**Q2: How do you perform basic plotting with Matplotlib in Python?****A2:** Basic plotting with Matplotlib involves creating plots such as histograms, bar charts, pie charts, box plots, and violin plots using functions like `plt.hist()`

, `plt.bar()`

, `plt.pie()`

, `plt.boxplot()`

, and `plt.violinplot()`

.

```
# Example of creating a histogram with Matplotlib
import matplotlib.pyplot as plt
data = [1, 2, 3, 4, 5]
plt.hist(data)
plt.show()
```

**Q3: How can you create a box plot and a violin plot using Matplotlib in Python?****A3:** You can create a box plot using `plt.boxplot()`

and a violin plot using `plt.violinplot()`

functions in Matplotlib.

```
# Example of creating a box plot with Matplotlib
plt.boxplot(data)
# Example of creating a violin plot with Matplotlib
plt.violinplot(data)
```

**Q4: What is the Seaborn library used for in Python?****A4:** Seaborn is a Python visualization library based on Matplotlib that provides a high-level interface for creating attractive and informative statistical graphics. It is particularly useful for visualizing complex datasets and for creating visually appealing plots with minimal code.

```
# Example of importing Seaborn
import seaborn as sns
```

**Q5: How do you create multiple plots using Seaborn in Python?****A5:** You can create multiple plots using Seaborn by using functions like `sns.pairplot()`

for pairwise relationships between variables and `sns.FacetGrid()`

for creating a grid of subplots based on one or more categorical variables.

```
# Example of creating a pairplot with Seaborn
sns.pairplot(data)
# Example of creating multiple plots using FacetGrid in Seaborn
g = sns.FacetGrid(data, col="category")
g.map(sns.histplot, "value")
```

**Q6: What is the purpose of the regplot() function in Seaborn?**

**A6:**The

`regplot()`

function in Seaborn is used to plot data and a linear regression model fit. It shows the relationship between two variables along with a regression line, confidence intervals, and a scatter plot of the data points.```
# Example of creating a regression plot with Seaborn
sns.regplot(x="x_variable", y="y_variable", data=data)
```

**Q7: How can you customize plots in Seaborn to improve their appearance?****A7:** You can customize plots in Seaborn by modifying various aesthetics such as colors, markers, line styles, labels, titles, and axis ticks using functions like `sns.set_style()`

, `sns.set_palette()`

, and `sns.despine()`

.

```
# Example of customizing plot aesthetics with Seaborn
sns.set_style("whitegrid")
sns.set_palette("pastel")
sns.despine(left=True)
```

**Q8: Can you create a pie chart using Seaborn in Python?****A8:** Seaborn does not have a direct function for creating pie charts. However, you can use Matplotlib’s `plt.pie()`

function for creating pie charts in Python.

```
# Example of creating a pie chart with Matplotlib
labels = ['A', 'B', 'C', 'D']
sizes = [15, 30, 45, 10]
plt.pie(sizes, labels=labels, autopct='%1.1f%%')
plt.show()
```

**Q9: How do you create a bar chart with Seaborn in Python?****A9:** Seaborn does not have a direct function for creating bar charts. However, you can use Matplotlib’s `plt.bar()`

function for creating bar charts in Python.

```
# Example of creating a bar chart with Matplotlib
x = ['A', 'B', 'C', 'D']
y = [10, 20, 15, 25]
plt.bar(x, y)
plt.show()
```

**Q10: How does Seaborn complement Matplotlib in Python?****A10:** Seaborn complements Matplotlib by providing a higher-level interface for creating visually appealing statistical graphics with less code. It builds on top of Matplotlib’s functionality and integrates seamlessly with Pandas data structures, making it easier to visualize complex datasets.

## Conclusion:

The viva questions presented here cover a range of topics from the syllabus of Data Analytics and Visualization as per the curriculum of DAV. These questions delve into essential concepts such as data import/export, data types, descriptive statistics, plotting and visualization techniques using both Matplotlib and Seaborn libraries in Python, and the application of text mining techniques.

While the answers provided have been prepared and verified by AI, it’s essential to acknowledge that automated responses may occasionally contain inaccuracies or limitations. Therefore, it’s advisable to cross-verify information from reliable sources and consult with instructors or subject matter experts for clarification when necessary.

Overall, these viva questions serve as a valuable resource for students preparing for examinations or interviews in the field of data analytics and visualization. They cover fundamental concepts and practical applications, providing a comprehensive understanding of the subject matter outlined in the syllabus.

Some Websites to Learn about Data Visualiation : https://www.geeksforgeeks.org/data-visualization-in-r/

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