standardvariation for certain rows

Question

I have a long dataset with different type of questions referred to in the case row.

age <- ("18-30","31-45","60+","46-60", "31-45", "18-30", "60+", "46-60")
gender <- ("M","F","F","F","M","M","F","M")
case <- ("Q1","Q1","Q2","Q2","Q3","Q3","Q4","Q4")
height <- (0,200,310,0,0,175,270,150)

I would like to calculate, the mean, the median and standard deviation per question for the height column. So 4 different tables for Q1, Q2, Q3 and Q4. I my knowledge of r is really limited anyone can help me with it please? thanks in advance

Answer 1

library(dplyr)
df <- tibble(
  age = c("18-30","31-45","60+","46-60", "31-45", "18-30", "60+", "46-60"),
gender = c("M","F","F","F","M","M","F","M"),
case = c("Q1","Q1","Q2","Q2","Q3","Q3","Q4","Q4"),
height = c(0,200,310,0,0,175,270,150)
)

df %>% 
  group_by(case) %>% 
  summarise(mean = mean(height), 
            median = median(height), 
            sd = sd(height))

If you want individual dataframes for each case, you can simply filter for the questions you want, i.e. for the first case "Q1"

df  %>% 
      group_by(case) %>% 
      summarise(mean = mean(height), 
                median = median(height), 
                sd = sd(height)) %>%
      filter(case == "Q1")