Dr. Arbuthnot’s Baptism records

The Arbuthnot data set refers to the work of Dr. John Arbuthnot, an 18th century physician, writer, and mathematician. He was interested in the ratio of newborn boys to newborn girls, so he gathered the baptism records for children born in London for every year from 1629 to 1710

Some Exploration

Exercise 1: What command would you use to extract just the counts of girls baptized?

arbuthnot$girls
##  [1] 4683 4457 4102 4590 4839 4820 4928 4605 4457 4952 4784 5332 5200 4910 4617
## [16] 3997 3919 3395 3536 3181 2746 2722 2840 2908 2959 3179 3349 3382 3289 3013
## [31] 2781 3247 4107 4803 4881 5681 4858 4319 5322 5560 5829 5719 6061 6120 5822
## [46] 5738 5717 5847 6203 6033 6041 6299 6533 6744 7158 7127 7246 7119 7214 7101
## [61] 7167 7302 7392 7316 7483 6647 6713 7229 7767 7626 7452 7061 7514 7656 7683
## [76] 5738 7779 7417 7687 7623 7380 7288

Data Visualization: Number of Girls Baptized per Year

# scatterplot of baptisms for girls by year
ggplot(data = arbuthnot, aes(x = year, y = girls)) + 
  geom_point()

#line plot over time for girl baptisms
ggplot(data = arbuthnot, aes(x = year, y = girls)) +
  geom_line()

Exercise 2: Is there an apparent trend in the number of girls baptized over the years? How would you describe it?

Prior to 1640, the number of girls baptized ranged from about….BE SURE to WRITE a COMPLETE description here. Do some research to see why we see significant drops in the data.

Adding a new variable to the data frame

#add a new column to data frame called total
arbuthnot <- arbuthnot %>%
  mutate(total = boys + girls)
#add another column that computes the proportion of boys baptized
arbuthnot <- arbuthnot %>%
  mutate(boy_ratio = boys / total)

Exercise 3: Plot the proportion of boys born over time. What do you see?

ggplot(data = arbuthnot, aes(x = year, y = boy_ratio)) +
  geom_line()

Over the time period that Dr. Arbuthnot collected the data of baptisms, the ratio of boys baptized was always higher than 50%. It was at its highest in 1661 when 53.6% of the baptisms were boys.

More Practice: Answer the following questions using the “present” data frame.

Exercise 4 What years are included in this data set? What are the dimensions of the data frame? What are the variable (column) names?

SHOW the CODE and WRITE YOUR ANSWER to Exercise 4 here.

Exercise 5: How do these counts compare to Arbuthnot’s? Are they of a similar magnitude?

SHOW the CODE and WRITE YOUR ANSWER to Exercise 5 here.

Exercise 6: Make a plot that displays the proportion of boys born over time. What do you see? Does Arbuthnot’s observation about boys being born in greater proportion than girls hold up in the U.S.? Include the plot in your response.

SHOW the CODE, MAKE a PLOT and WRITE YOUR ANSWER to Exercise 6 here.

Exercise 7: In what year did we see the most total number of births in the U.S.?

SHOW the CODE and WRITE YOUR ANSWER to Exercise 7 here.