CompTIA CompTIA Data+ DA0-001 Questions & Answers

• Question 21:

  `Which of the following is the BEST reason to use database views instead of tables?

  A. Views reduce the need for repetitive, complex data joins.

  B. Views allow for the storage of temporary data. whereas tables do not.

  C. Views allow for the joining of multiple data sources, whereas tables do not.

  D. Views can be used to restrict sensitive information.

  Correct Answer: A

  Explanation: Views are virtual tables that are created by querying one or more base tables or other views. Views do not store any data, but only show the result of a query. One of the main advantages of using views is that they can reduce the need for repetitive, complex data joins. For example, if a query involves joining multiple tables with many conditions, creating a view can simplify the query and make it easier to reuse. Therefore, the correct answer is A. References: [What is a Database View? | Definition and Examples - Vertabelo], [Database Views - GeeksforGeeks]

• Question 22:

  Which of the following is a characteristic of a relational database?

  A. It utilizes key-value pairs.

  B. It has undefined fields.

  C. It is structured in nature.

  D. It uses minimal memory.

  Correct Answer: C

  Explanation: It is structured in nature. This is because a relational database is a type of database that organizes data into tables, which consist of rows and columns. A relational database is structured in nature, which means that the data has a predefined schema or format, and follows certain rules and constraints, such as primary keys, foreign keys, or referential integrity. A relational database can be used to store, query, and manipulate data using a structured query language (SQL). The other characteristics are not true for a relational database. Here is why:

  It utilizes key-value pairs. This is not true for a relational database, because key-value pairs are a way of storing data that associates each value with a unique key, such as an identifier or a name. Key-value pairs are typically used in non-relational databases, such as NoSQL databases, which do not have tables, rows, or columns, but rather store data in various formats, such as documents, graphs, or columns. It has undefined fields. This is not true for a relational database, because fields are another name for columns in a table, which define the attributes or properties of each row or record in the table. Fields have defined names, types, and lengths in a relational database, which specify the format and size of the data that can be stored in each field. It uses minimal memory. This is not true for a relational database, because memory is the amount of space or storage that is used by a database to store and process data. Memory usage depends on various factors, such as the size, complexity, and number of tables and queries in a relational database. A relational database can use a lot of memory if it has many tables with many rows and columns, or if it performs complex or frequent queries on the data.

• Question 23:

  Which of the ing is the correct ion for a tab-delimited spre file?

  A. tap

  B. tar

  C. sv

  D. az

  Correct Answer: C

  Explanation: A tab-delimited spreadsheet file is a type of flat text file that uses tabs as delimiters to separate data values in a table. The file extension for a tab-delimited spreadsheet file is usually .tsv, which stands for tab-separated values. Therefore, the correct answer is C. References: [Tab-separated values - Wikipedia], [What is a TSV File? | How to Open, Edit and Convert TSV Files]

• Question 24:

  An analyst modified a data set that had a number of issues. Given the original and modified versions:

  

  Which of the following data manipulation techniques did the analyst use?

  A. Imputation

  B. Recoding

  C. Parsing

  D. Deriving

  Correct Answer: B

  The correct answer is B. Recoding.

  Recoding is a data manipulation technique that involves changing the values or categories of a variable to make it more suitable for analysis. Recoding can be used to simplify or group the data, to correct errors or inconsistencies, or to create

  new variables from existing ones12

  In the example, the analyst used recoding to change the values of Var001, Var002, Var003, and Var004 from numerical to textual form. The analyst also used recoding to assign meaningful labels to the values, such as "Absent" for 0,

  "Present" for 1, "Low" for 2, "Medium" for 3, and "High" for 4. This makes the data more understandable and easier to analyze.

• Question 25:

  What SQL command is used to delete an entire table from a database?

  A. DROP.

  B. MODIFY.

  C. DELETE.

  D. ALTER.

  Correct Answer: A

• Question 26:

  A data set was recorded using multimedia technology. Which of the following is a necessary step on the way to interpretation?

  A. Structural equation modeling

  B. Transcription

  C. Sequential analysis

  D. Sampling

  Correct Answer: B

  The correct answer is B. Transcription.

  Transcription is a necessary step on the way to interpretation when a data set was recorded using multimedia technology. Multimedia technology refers to the use of various forms of media, such as audio, video, images, and text, to capture

  and present information1 Transcription is the process of converting multimedia data into written or textual form, which can then be analyzed using various methods and tools2 Transcription can help to make the data more accessible,

  searchable, and manageable, as well as to preserve the data for future use.

  Structural equation modeling is not correct, because it is a statistical technique that tests the causal relationships between multiple variables using observed and latent variables. Structural equation modeling is not a necessary step on the

  way to interpretation, but rather an optional method that can be applied to certain types of data. Sequential analysis is not correct, because it is a method of analyzing the order and timing of events or behaviors in a data set. Sequential

  analysis is not a necessary step on the way to interpretation, but rather an optional method that can be applied to certain types of data. Sampling is not correct, because it is the process of selecting a subset of data from a larger population for

  analysis. Sampling is not a necessary step on the way to interpretation, but rather a preliminary step that can be done before collecting or analyzing the data.

• Question 27:

  Which of the following are reasons to create and maintain a data dictionary? (Choose two.)

  A. To improve data acquisition

  B. To remember specifics about data fields

  C. To specify user groups for databases

  D. To provide continuity through personnel turnover

  E. To confine breaches of PHI data

  F. To reduce processing power requirements

  Correct Answer: AB

  Explanation: The reasons to create and maintain a data dictionary are to improve data acquisition and to remember specifics about data fields. A data dictionary is a document or a database that describes the structure, meaning, and usage of the data elements in a data source or a database. A data dictionary can help to improve data acquisition by providing clear and consistent definitions, rules, and standards for the data collection process. A data dictionary can also help to remember specifics about data fields by providing information such as data type, format, length, range, default value, constraints, relationships, etc. The other options are not reasons to create and maintain a data dictionary, as they are related to other aspects of data management or security. A data dictionary does not specify user groups for databases, as this is a function of access control or authorization. A data dictionary does not provide continuity through personnel turnover, as this is a function of documentation or knowledge transfer. A data dictionary does not confine breaches of PHI data, as this is a function of encryption or anonymization. A data dictionary does not reduce processing power requirements, as this is a function of optimization or compression. Reference: [What is a Data Dictionary? - DataCamp]

• Question 28:

  Analytics reports should follow corporate style guidelines.

  A. True.

  B. False.

  Correct Answer: A

• Question 29:

  A research analyst collects ten data points from 1.000 specimens. The analyst will not need any additional data to complete the analysis and will not need to retrieve information by specifier. Which of the following is the best data structure for the analyst to use?

  A. NoSQL

  B. Flat file

  C. JSON

  D. Relational database

  Correct Answer: B

  A flat file is a type of data structure that stores data in a plain text format, such as CSV, TSV, or TXT. A flat file consists of one or more records, each containing one or more fields, separated by a delimiter, such as a comma, tab, or space. A

  flat file does not have any hierarchical or relational structure, and does not support any complex queries or operations1.

  A flat file may be the best data structure for the analyst to use in this scenario, because:

  The analyst collects ten data points from 1,000 specimens, which means the data is relatively small and simple, and can be easily stored and processed in a flat file. The analyst will not need any additional data to complete the analysis, which

  means the data is static and does not require any updates or modifications. The analyst will not need to retrieve information by specifier, which means the data does not require any indexing or searching by key or value.

• Question 30:

  Which of the following statements would be used to append two tables that have the same number of columns?

  A. UNION ALL

  B. MERGE

  C. GROUP BY

  D. JOIN

  Correct Answer: A

  The correct answer is A. UNION ALL.

  UNION ALL is a SQL statement that appends two tables that have the same number of columns and compatible data types. UNION ALL preserves all the rows from both tables, including any duplicates12

  B. MERGE is not correct, because MERGE is a SQL statement that combines the data of two tables based on a common column. MERGE can perform insert, update, or delete operations on the target table depending on the matching or non-matching rows from the source table34

  C. GROUP BY is not correct, because GROUP BY is a SQL clause that groups the rows of a table based on one or more columns. GROUP BY is often used with aggregate functions, such as SUM, AVG, COUNT, etc., to calculate summary statistics for each group56 D. JOIN is not correct, because JOIN is a SQL clause that combines the data of two tables based on a common column or condition. JOIN can produce different results depending on the type of join, such as INNER JOIN, LEFT JOIN, RIGHT JOIN, etc.