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A data refresh is a documentation element that indicates when the data was last updated or refreshed from the source. A data refresh can help the analyst to catch the error of the data warehouse not updating the data, as it will show a discrepancy between the expected and actual date of the data update. A data refresh can also help the users of the report to verify the timeliness and accuracy of the data, and to avoid making decisions based on outdated or incorrect data

Comprehensive and Detailed In-Depth Explanation:

To compile a comprehensive annual revenue report from multiple quarterly sales reports, the analyst should integrate the datasets appropriately:

Data Merge: This technique involves combining datasets based on common fields or keys. In this scenario, merging would align data from different quarters based on shared attributes, such as location identifiers, to create a unified dataset.

Data Append: Appending adds datasets sequentially, stacking them on top of each other. While this could combine the reports, it doesn't ensure integration based on common fields, which is necessary for accurate analysis.

Data Blending: Blending combines data from different sources or formats. If the quarterly reports are in varied formats or from different systems, blending would be appropriate. However, if they share the same structure, blending isn't necessary.

Data Imputation: Imputation addresses missing or incomplete data by filling in gaps. This technique isn't relevant to combining complete quarterly reports.

Therefore, merging the data ensures that all quarterly reports are integrated based on common fields, providing a cohesive annual revenue report.

Comprehensive and Detailed In-Depth Explanation:

A confidence interval provides a range within which we expect a population parameter to lie, based on sample data. Increasing the confidence level means we want to be more certain that the interval contains the parameter, which affects the margin of error.

Option A:The margin of error does not change.

Rationale:This is incorrect. Increasing the confidence level requires a wider interval to maintain the higher degree of certainty, which increases the margin of error.

Option B:The interval remains the same.

Rationale:This is incorrect. To achieve a higher confidence level, the interval must widen, altering its range.

Option C:The interval becomes narrower.

Rationale:This is incorrect. A higher confidence level necessitates a wider interval to ensure the parameter is captured within the range.

Option D:The margin of error increases.

Rationale:Correct. Increasing the confidence level from 90% to 95% means we are more confident that the interval contains the true parameter. To achieve this increased confidence, the margin of error must increase, resulting in a wider interval.

Exploratory Data Analysis (EDA) is a technique used to summarize the main characteristics of a dataset. It often involves using graphical representations and statistical summaries to uncover patterns, relationships, and anomalies in the data. Analysts perform EDA to detect outliers, missing values, and trends before proceeding with deeper data processing and modeling​.