Quiz 1

Classwork 6

Descriptive Statistics

The following provides the percentage of the correct answers for each question in Quiz 1:

Question 1. data.frame

In a data frame, what form does a variable take?

Answer: Column

• This slide in Lecture 7 explains what makes a data.frame tidy. In our course, all given data.frames are tidy.

Question 2. left_join()

df_joined <- df_1 |> ___(df_2)

• Fill in the blank (___) to join the two related data.frames, df_1 and df_2, in a way that keeps all observations and variables in the data.frame df_1.

Answer: left_join

df_joined <- df_1 |> left_join(df_2)

• This slide in Lecture 10 and this slide in Lecture 11 explain join and left_join().

Question 3. == (Equality operator)

df_filtered <- df |> filter(num __ 9) 

• Fill in the blank (___) to keep observations, in which the value of the num variable is equal to 9.

Answer: ==

df_filtered <- df |> filter(num == 9) 

• This slide and this slide in Lecture 11 explain an equality operator, == (equal to).

Question 4. != (Not-equal operator)

non_dec <- df |> filter(month ___ 12)

• Fill in the blank (___) to keep observations, in which the value of the month is not equal to 12 in the data.frame df

Answer: !=

non_dec <- df |> filter(month != 12)

• This slide and Line 105-106 in this class R script in Lecture 11 explain a not-equal operator, != (not equal to).

Question 5. | (Or operator)

df_filtered <- df |> filter(subject == "DANL" ___ subject == "ECON")

• Fill in the blank (___) to keep observations, in which the value of the subject variable is either “DANL” or “ECON”

Answer: |

df_filtered <- df |> filter(subject == "DANL" | subject == "ECON")

• This slide and this slide in Lecture 11 explain logical operation, | (or).

• Please note that | is not the letter “I” or “l,” but a vertical bar character.

• On a keyboard, | is located above the Enter/Return key.

Discussion

Welcome to our Quiz 1 Discussion Board! 👋

This space is designed for you to engage with your classmates about the material covered in Quiz 1.

Whether you are looking to delve deeper into the content, share insights, or have questions about the content, this is the perfect place for you.

If you have any specific questions for Byeong-Hak (@bcdanl) or peer classmate (@GitHub-Username) regarding the Quiz 1 materials or need clarification on any points, don’t hesitate to ask here.

Let’s collaborate and learn from each other!