Data Analysis in R: Summary and Assessment
Knowledge Check
Quiz
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Knowledge Check
Quiz
Knowledge Check
Answer these questions to check understanding.
What is the main purpose of descriptive analysis in clinical data management?
- A. To summarize collected data for review, monitoring, and reporting.
- B. To replace the protocol.
- C. To remove all missing values automatically.
- D. To guarantee statistical significance.
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Answer: A
Why is the unit of observation important?
- A. Because rows may represent participants, visits, events, or test results.
- B. Because R cannot count rows.
- C. Because all datasets have one row per participant.
- D. Because it only affects graphics.
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Answer: A
Which function is commonly used to count records by category?
- A. `count()`
- B. `install.packages()`
- C. `read_csv()`
- D. `getwd()`
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Answer: A
Why should missing values often be shown in data management summaries?
- A. Because missingness is itself a data quality issue.
- B. Because missing values should always be treated as zero.
- C. Because missing values cannot affect interpretation.
- D. Because R requires missing values to be printed.
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Answer: A
In a visit-level dataset, what does `n()` count?
- A. Rows or visits.
- B. Always unique participants.
- C. Only completed participants.
- D. Only missing values.
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Answer: A
What does `n_distinct(participant_id)` count?
- A. The number of unique participant identifiers.
- B. The number of variables in the dataset.
- C. The number of missing values.
- D. The number of R packages loaded.
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Answer: A
What is a common risk when joining enrollment data to laboratory data?
- A. Participant rows may multiply if there are multiple lab records per participant.
- B. R will delete all laboratory results automatically.
- C. Joins cannot affect row counts.
- D. Joins are only used for graphics.
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Answer: A
Why should counts usually be shown with percentages?
- A. Percentages can be misleading when denominators are small or unclear.
- B. Counts are never useful.
- C. Percentages always add to exactly 100 after rounding.
- D. R cannot calculate percentages.
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Answer: A