10+ HT Systems Interview Questions and Answers

ML data preparation involves cleaning, transforming, and organizing data for analysis. EDA involves exploring and visualizing data to understand its characteristics.

• Data cleaning: removing missing values, handling outliers, and dealing with duplicates

• Data transformation: encoding categorical variables, scaling numerical features, and creating new features

• Data organization: splitting data into training and testing sets, and handling imbalanced classes

• Exploratory Data Analysis ...read more

Data analysis is the process of inspecting, cleaning, transforming, and modeling data to discover useful information.

• It involves collecting and organizing data

• It includes statistical analysis and visualization

• It helps in making informed decisions

• Examples include market research, financial analysis, and scientific research

SQL Queries using Joins and sub-queries

• Joins are used to combine rows from different tables based on a related column

• Sub-queries are queries nested within another query

• Joins and sub-queries can be used together to retrieve specific data from multiple tables

CLT theorem states that the distribution of sample means approaches a normal distribution as sample size increases.

• Central Limit Theorem (CLT) is a fundamental concept in statistics that states that the distribution of sample means approaches a normal distribution as the sample size increases.

• It is used in hypothesis testing, confidence intervals, and in estimating population parameters.

• CLT is essential in making inferences about a population based on sample data.

• For example,...read more

Answering questions related to SQL joins, lambda function in Python, and difference between tuples and lists.

• There are four types of joins in SQL: inner join, left join, right join, and full outer join.

• Lambda function is an anonymous function in Python that can take any number of arguments, but can only have one expression.

• Tuples are immutable and ordered collections of elements, while lists are mutable and ordered collections of elements.

• Example of SQL join: SELECT * FROM ta...read more

LatentView offers a dynamic work environment with opportunities for growth and learning in the field of analytics.

• LatentView has a strong reputation in the analytics industry for delivering innovative solutions to clients.

• The company values continuous learning and development, providing employees with opportunities to enhance their skills.

• LatentView offers a collaborative work culture where employees can work on diverse projects and learn from experienced professionals.

• The co...read more

Latent view and analytics are essential for data-driven decision making. My best achievement is developing a predictive model for customer churn.

• Latent view helps to uncover hidden patterns and insights in data that are not immediately apparent.

• Analytics provides a systematic approach to analyzing data and extracting meaningful insights.

• My best achievement is developing a predictive model for customer churn that helped reduce churn rate by 20%.

Approximately 1.5-2 million cars are sold in Delhi annually.

• Consider population of Delhi (approx. 20 million)

• Assume car ownership rate (approx. 10%)

• Factor in replacement rate and new buyers

UNION combines and removes duplicates, UNION ALL combines without removing duplicates.

• UNION merges the results of two or more SELECT statements and removes duplicates.

• UNION ALL merges the results of two or more SELECT statements without removing duplicates.

• UNION is slower as it has to remove duplicates, while UNION ALL is faster.

• Example: SELECT column1 FROM table1 UNION SELECT column1 FROM table2;

• Example: SELECT column1 FROM table1 UNION ALL SELECT column1 FROM table2;

Query to output the name of credit card and number of cards issued in launch month

• Use GROUP BY to group by launch month

• Count the number of cards issued in each launch month

• Select the name of the credit card and the count of cards issued

SQL commands include SELECT, INSERT, UPDATE, DELETE, CREATE, and DROP.

• SELECT: retrieves data from a database

• INSERT: adds new records to a table

• UPDATE: modifies existing records in a table

• DELETE: removes records from a table

• CREATE: creates a new table, view, or index

• DROP: deletes a table or index

Query to retrieve the third transaction of every user

• Use a subquery to rank the transactions for each user

• Filter the results to only include the third transaction for each user

Random forest decides variables based on feature importance and information gain.

• Random forest calculates feature importance by measuring how much the tree nodes that use a particular feature reduce impurity.

• Variables with higher feature importance are considered more important in making predictions.

• Random forest also uses information gain to decide which variables to split on at each node in the trees.

• The variables that result in the highest information gain are chosen for s...read more

Gini index is a measure of impurity used in decision trees for variable selection.

• Gini index ranges from 0 (pure node) to 0.5 (impure node)

• Variables with lower Gini index are preferred for splitting

• Higher Gini index indicates higher impurity and less predictive power

Group employees by department with salary > 50,000 in SQL.

• Use GROUP BY clause to group employees by department.

• Use WHERE clause to filter employees with salary > 50,000.

• Example: SELECT department, COUNT(employee_id) FROM employees WHERE salary > 50000 GROUP BY department;

Use SQL query to select employees with odd employee IDs.

• Use the modulo operator (%) to check if employee ID is odd (e.g. id % 2 = 1)

• Write SQL query like 'SELECT * FROM employees WHERE employee_id % 2 = 1;'

Use SQL query with ORDER BY and LIMIT to find 2nd max number from a column in a table.

• Use SELECT MAX(column_name) to find the max number in the column.

• Use SELECT column_name FROM table_name ORDER BY column_name DESC LIMIT 1,1 to find the 2nd max number.

• Example: SELECT column_name FROM table_name ORDER BY column_name DESC LIMIT 1,1;

Implementing logics in a use case study to analyze data and derive insights.

• Identify the problem statement and objectives of the study

• Collect relevant data and clean it for analysis

• Apply statistical and machine learning techniques to derive insights

• Interpret the results and communicate findings to stakeholders