Free Data Science Analysis Question and Answers 1 — Questions and Answers
Question 1: On a bank's website, information has been gathered about visitors' viewing patterns. Which method is employed to determine which pages are frequently viewed simultaneously on the website?
- Regression
- Classification
- Clustering
- Association Rules (Correct answer)
Correct answer: Association Rules
Association rules are a data mining technique used to discover relationships between variables in large datasets, often expressed as 'if-then' statements. In the context of a bank's website, they can identify which pages are frequently viewed together in user sessions. This method helps uncover patterns of co-occurrence, useful for understanding user behavior and making recommendations.
Question 2: The task of creating a model from a reporting data warehouse is given to a data scientist. The warehouse houses data that has been processed through a difficult, multi-stage ETL process using data gathered from numerous sources. What should the data scientist be worried about in terms of the data?
- It is not structured
- It is too centralized
- It is too processed (Correct answer)
- It is not normalized
Correct answer: It is too processed
Data in a reporting data warehouse, especially after a complex multi-stage ETL process, is often highly aggregated, transformed, and summarized for specific reporting needs. While beneficial for reporting, this extensive processing can remove granular details, introduce biases, or obscure relationships crucial for building robust predictive models. Data scientists often prefer less processed data to ensure model accuracy and flexibility.
Question 3: When would a Wilcoxson Rank Sum test be appropriate?
- When the data can easily be sorted
- When the populations represent the sums of other values
- When the data cannot easily be sorted
- When you cannot make an assumption about the distribution of the populations (Correct answer)
Correct answer: When you cannot make an assumption about the distribution of the populations
The Wilcoxon Rank Sum test, also known as the Mann-Whitney U test, is a non-parametric statistical test. It is appropriate when comparing two independent groups and you cannot make assumptions about the underlying distribution of the populations, such as normality. This test ranks the data and compares the sums of the ranks between the groups.
Question 4: What data science requirement is the most fundamental?
- Learn/Optimize
- Collect (Correct answer)
- Explore/ Transform
- Move/Store
Correct answer: Collect
Data collection is the most fundamental requirement in data science. Without data, there is nothing to analyze, transform, model, or learn from. All subsequent steps in the data science pipeline, such as exploration, cleaning, storage, and model building, are entirely dependent on having relevant and accessible data.
Question 5: What role does the Reduce function play in the MapReduce framework?
- It breaks the input into smaller components and distributes it to other nodes in the cluster.
- It writes the output of the Map function to storage.
- It aggregates the results of the Map function and generates processed output.
- It distributes the input to multiple nodes for processing. (Correct answer)
Correct answer: It distributes the input to multiple nodes for processing.
In the MapReduce framework, the Reduce function processes the intermediate key-value pairs generated by the Map tasks. Before reaching the Reduce function, these intermediate results are shuffled and sorted, effectively distributing them to the appropriate reducer tasks across multiple nodes. Thus, the Reduce function is a crucial component in the overall distributed processing pipeline, working on data that has been distributed for aggregation.
Question 6: Therefore, recommendations may only be made based on the tone and topic matter of the present article. The magazine's whole collection of articles is kept in a database in a manner that is suited for analytics. Which approach ought the data scientist to test out first?
- Association Rules
- Logistic Regression
- K Means Clustering (Correct answer)
- None of the above
Correct answer: K Means Clustering
When recommendations are based on the 'tone and topic matter' of articles, the goal is to group similar articles together. K-Means Clustering is an unsupervised machine learning algorithm that partitions data points into 'k' distinct clusters, where articles within the same cluster share similar characteristics. This approach would effectively group articles with comparable content and tone, enabling relevant recommendations.
Question 7: When you send a MapReduce task to a Hadoop cluster, you discover that even though it was sent successfully, the job has not yet been finished. What ought you to do?
- Ensure that the JobTracker is running
- Ensure that the TaskTracker is running (Correct answer)
- Ensure that a datanode is running
- Ensure that the NameNode is running
Correct answer: Ensure that the TaskTracker is running
In older Hadoop 1.x architectures, the TaskTracker was responsible for executing individual Map and Reduce tasks on the data nodes. If a MapReduce job has been successfully sent but is not finishing, it indicates that the tasks themselves are not being executed. Therefore, ensuring the TaskTracker (or its equivalent, the NodeManager in Hadoop 2.x+) is running is crucial for job execution.
Free Data Science Analysis Question and Answers 1
On a bank's website, information has been gathered about visitors' viewing patterns.
Which method is employed to determine which pages are frequently viewed simultaneously on the website?