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Installing R and RStudio1 Lesson2 Quizzes
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The RStudio IDE1 Lesson2 Quizzes
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Coding Basics1 Lesson2 Quizzes
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Assignment | Workshop 11 Quiz
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Data dive: Ebola in Sierra Leone1 Lesson2 Quizzes
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RStudio Projects1 Lesson2 Quizzes
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Workshop 21 Lesson1 Quiz
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Using R Markdown1 Lesson2 Quizzes
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Data classes & structures (deprec)2 Lessons
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Workshop 31 Lesson1 Quiz
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Select & rename1 Lesson3 Quizzes
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Filter1 Lesson3 Quizzes
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Workshop 41 Quiz
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Mutate1 Lesson3 Quizzes
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Workshop 51 Lesson1 Quiz
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Conditional mutate1 Lesson3 Quizzes
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Group by and summarize1 Lesson2 Quizzes
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Workshop 61 Lesson1 Quiz
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Other grouped operations1 Lesson2 Quizzes
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Workshop 71 Lesson1 Quiz
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Intro to ggplot21 Lesson2 Quizzes
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Scatter plots and smoothing1 Lesson2 Quizzes
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Workshop 81 Lesson1 Quiz
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Lines, scales, and labels1 Lesson2 Quizzes
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Overview of the EpiGraphHub web platform
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Data exploration on EpiGraphHub1 Quiz
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Workshop 91 Lesson1 Quiz
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Workshop 101 Lesson1 Quiz
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Final project1 Lesson1 Quiz
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Getting help1 Lesson1 Quiz
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Quiz contributions16 Lessons
Participants 76
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Lesson code
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Lesson notes
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data quiz question: Could someone explain why I have Cov=4.2 instead of 0.015 ? Please see my codes below. covid_well_being_1 <- covid_well_being |> mutate(sleep_time=minutes_from_sleep_to_wake – minutes_awake_at_night) covid_well_being_1 sleep_time_and_stress <- covid_well_being_1 %>% group_by(respondent_id) %>% summarize (mean_sleep_time = mean(sleep_time, na.rm = T), mean_stress_levels = mean(stress_1_low_7_high, na.rm = T) ) sleep_time_and_stress sleep_time_and_stress |> signif(digits = 3) cov(x=sleep_time_and_stress$mean_sleep_time, y=sleep_time_and_stress$mean_stress_levels) |>… Read more »
Hi Samuel, I think it may be because you use cov () instead of cor (). I looked at chatGPT and it says cor () is used to compute the correlation coefficient between variables while cov () is used to compute the covariance between variables. Please try with cor () as we are… Read more »
Nice catch, Cicilia!
Samuel, apart from the small typo in your function name that Cicilia mentioned, your code looks good to me. I hope you are able to try the suggested solution and resolve the issue.
Joy, thank you. I have resolved the issue thanks to Cicilia. However, I have already submitted the data quiz and missed the related question.
Dear Tutor, could you please advise if we should use ungroup () function systematically after the group_by () and summarize () functions are being used? Thank you.
Hi Cicilia, good question. If you intend to use your summarized data frame for further manipulations — e.g., with mutate() or select() — you should add ungroup() after group_by() and summarize(), otherwise it will likely produce errors down the line. However, if you are creating a summary table which you don’t plan to… Read more »
Thanks for this advice, Joy. Very useful.
Hello Team. Could anyone explain why the question check said this is incorrect ?
Q_sum_bedridden_days <-
yao %>% group_by(sex) %>% summarize(total_bedridden_days = sum(n_days_miss_work, na.rm = TRUE))
Q_sum_bedridden_days
Hi Samuel, from your code, I could see that you use variable n_days_miss_work to calculate total bedridded_days. That’s why it’s incorrect. You may want to use n_bedridden_days instead.
thank you. Resolved
Requesting a support for the quiz on this lesson Dear Graph Team, I would ask a support from you about this quiz. I have done this quiz and I got 142,1% and I click on button “send” for submit it. We tell me that it’s submitted and it told me that I got… Read more »
Now the problem is resolved
Hello, please there seems to be a problem with how the system is checking the answers to the questions.
Sorry about the issue! This has now been fixed. Thanks for noticing.