Data Cleaning Fundamentals

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Questions and Answers

Which of the following best describes the primary goal of data cleaning?

  • To maintain data quality and accuracy by correcting or removing errors and inconsistencies. (correct)
  • To reduce the size of datasets for efficient storage.
  • To transform data into a format suitable for visualization.
  • To add more data points to ensure comprehensive analysis.

Data cleaning is a one-time process and does not need to be repeated as long as the data source remains the same.

False (B)

Name three common types of data inconsistencies that are addressed during data cleaning.

Inaccurate data, missing data, inconsistent formatting

The process of filling in missing values in a dataset is known as data ________.

<p>imputation</p> Signup and view all the answers

Match each data cleaning technique with its corresponding description:

<p>Data Deduplication = Removing duplicate entries to ensure unique records Data Formatting = Standardizing the structure and syntax of data values Outlier Removal = Identifying and removing extreme values that deviate significantly from the rest of the data Data Imputation = Filling in missing values with estimated or calculated values</p> Signup and view all the answers

Which statistical method is LEAST suitable for handling missing data in a dataset?

<p>Standard deviation (C)</p> Signup and view all the answers

Using the mean to impute missing values is always the best option, regardless of the data distribution.

<p>False (B)</p> Signup and view all the answers

When should outlier removal be approached with caution?

<p>When outliers are valid but unexpected data points. (D)</p> Signup and view all the answers

What is the purpose of data validation after the data cleaning process?

<p>Verifying data quality and accuracy</p> Signup and view all the answers

Which of the following is NOT a typical task in data transformation?

<p>Removing duplicate rows. (C)</p> Signup and view all the answers

Data transformation is solely about converting data from one file format to another.

<p>False (B)</p> Signup and view all the answers

_________ is a data transformation technique used to scale numerical data to a standard range, such as between 0 and 1.

<p>Normalization</p> Signup and view all the answers

Name two key considerations when choosing a data aggregation method.

<p>Data type; analysis purpose</p> Signup and view all the answers

What is the purpose of feature engineering in data preprocessing?

<p>To improve the performance of machine learning models by creating new features. (C)</p> Signup and view all the answers

Feature engineering is only useful for complex machine learning algorithms and not for simpler statistical analyses.

<p>False (B)</p> Signup and view all the answers

Which of the following is a common technique for handling categorical variables in machine learning?

<p>One-hot encoding (C)</p> Signup and view all the answers

Describe a scenario where binning a numerical feature might be useful prior to modeling.

<p>Data with outliers or non-linear relationships</p> Signup and view all the answers

________ scaling is a feature scaling technique that transforms the values to have a mean of 0 and a standard deviation of 1.

<p>Z-score</p> Signup and view all the answers

How can the effectiveness of different data preprocessing techniques be evaluated?

<p>By comparing model performance metrics on the preprocessed data. (C)</p> Signup and view all the answers

If a machine learning model performs poorly after applying a data preprocessing technique, it always indicates that the technique was implemented incorrectly.

<p>False (B)</p> Signup and view all the answers

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