RObservations #7 – #TidyTuesday – Analysing Coffee Ratings Data
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Introduction
Around four years ago I was given a copy of Time Magazine’s specialty issue on Coffee together with a French press as a gift. At the time, I was satisfied with a regular instant cup of joe and did not know much about the vastness and culture of the industry. However, it was thanks to these gifts that I was able to learn a lot about coffee, such as the two major species of beans (Arabica and Robusta),the tasting process done by connoisseurs to rank various coffees(called “cupping”), about the altitude, climate and countries various coffees grow around the world. If you read this specialty issue by Time, you probably not only got a more expensive interest piqued (if you haven’t already), but also probably learned enough to hold your own with the the best of the coffee snobs out there.
(PSA- this blog is not sponsored by Time Magazine, but I won’t say no if I got an offer!)
In this blog post we’re going to examine the coffee_ratings dataset released back in the beginning of July 2020 in the Tidy Tuesday Project by R4DS. I initially started analyzing this dataset seeking to answer a lot of questions. But, because there is so much to discover and analyze from this relatively small dataset, I thought it is best to try to focus my question on a very simple one:
Where in the world can I find the best coffee beans?
While this question seems simple enough. There is a lot to uncover to answer this question.
Our Data (Some Exploratory Data Analysis)
Loading our data
I am loading the data with the tidytuesdayR package, if you want you can load the raw data with the readr package’s read_csv() function as well.
A Quick Glimpse
library(tidyverse) coffee_ratings<-tuesdata$coffee_ratings glimpse(coffee_ratings) ## Rows: 1,339 ## Columns: 43 ## $ total_cup_points <dbl> 90.58, 89.92, 89.75, 89.00, 88.83, 88.83, 88.75, 88.67, 88.42, 88.25, 88.08, 87.92, 87.92, 87.92, 87.8... ## $ species <chr> "Arabica", "Arabica", "Arabica", "Arabica", "Arabica", "Arabica", "Arabica", "Arabica", "Arabica", "Ar... ## $ owner <chr> "metad plc", "metad plc", "grounds for health admin", "yidnekachew dabessa", "metad plc", "ji-ae ahn",... ## $ country_of_origin <chr> "Ethiopia", "Ethiopia", "Guatemala", "Ethiopia", "Ethiopia", "Brazil", "Peru", "Ethiopia", "Ethiopia",... ## $ farm_name <chr> "metad plc", "metad plc", "san marcos barrancas \"san cristobal cuch", "yidnekachew dabessa coffee pla... ## $ lot_number <chr> NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, "YNC-06114", NA, NA, NA, NA, N... ## $ mill <chr> "metad plc", "metad plc", NA, "wolensu", "metad plc", NA, "hvc", "c.p.w.e", "c.p.w.e", "tulla coffee f... ## $ ico_number <chr> "2014/2015", "2014/2015", NA, NA, "2014/2015", NA, NA, "010/0338", "010/0338", "2014/15", NA, "unknown... ## $ company <chr> "metad agricultural developmet plc", "metad agricultural developmet plc", NA, "yidnekachew debessa cof... ## $ altitude <chr> "1950-2200", "1950-2200", "1600 - 1800 m", "1800-2200", "1950-2200", NA, NA, "1570-1700", "1570-1700",... ## $ region <chr> "guji-hambela", "guji-hambela", NA, "oromia", "guji-hambela", NA, NA, "oromia", "oromiya", "snnp/kaffa... ## $ producer <chr> "METAD PLC", "METAD PLC", NA, "Yidnekachew Dabessa Coffee Plantation", "METAD PLC", NA, "HVC", "Bazen ... ## $ number_of_bags <dbl> 300, 300, 5, 320, 300, 100, 100, 300, 300, 50, 300, 10, 10, 1, 300, 10, 1, 150, 3, 250, 10, 250, 14, 1... ## $ bag_weight <chr> "60 kg", "60 kg", "1", "60 kg", "60 kg", "30 kg", "69 kg", "60 kg", "60 kg", "60 kg", "60 kg", "1 kg",... ## $ in_country_partner <chr> "METAD Agricultural Development plc", "METAD Agricultural Development plc", "Specialty Coffee Associat... ## $ harvest_year <chr> "2014", "2014", NA, "2014", "2014", "2013", "2012", "March 2010", "March 2010", "2014", "2014", "2014"... ## $ grading_date <chr> "April 4th, 2015", "April 4th, 2015", "May 31st, 2010", "March 26th, 2015", "April 4th, 2015", "Septem... ## $ owner_1 <chr> "metad plc", "metad plc", "Grounds for Health Admin", "Yidnekachew Dabessa", "metad plc", "Ji-Ae Ahn",... ## $ variety <chr> NA, "Other", "Bourbon", NA, "Other", NA, "Other", NA, NA, "Other", NA, "Other", "Other", NA, NA, "Othe... ## $ processing_method <chr> "Washed / Wet", "Washed / Wet", NA, "Natural / Dry", "Washed / Wet", "Natural / Dry", "Washed / Wet", ... ## $ aroma <dbl> 8.67, 8.75, 8.42, 8.17, 8.25, 8.58, 8.42, 8.25, 8.67, 8.08, 8.17, 8.25, 8.08, 8.33, 8.25, 8.00, 8.33, ... ## $ flavor <dbl> 8.83, 8.67, 8.50, 8.58, 8.50, 8.42, 8.50, 8.33, 8.67, 8.58, 8.67, 8.42, 8.67, 8.42, 8.33, 8.50, 8.25, ... ## $ aftertaste <dbl> 8.67, 8.50, 8.42, 8.42, 8.25, 8.42, 8.33, 8.50, 8.58, 8.50, 8.25, 8.17, 8.33, 8.08, 8.50, 8.58, 7.83, ... ## $ acidity <dbl> 8.75, 8.58, 8.42, 8.42, 8.50, 8.50, 8.50, 8.42, 8.42, 8.50, 8.50, 8.33, 8.42, 8.25, 8.25, 8.17, 7.75, ... ## $ body <dbl> 8.50, 8.42, 8.33, 8.50, 8.42, 8.25, 8.25, 8.33, 8.33, 7.67, 7.75, 8.08, 8.00, 8.25, 8.58, 8.17, 8.50, ... ## $ balance <dbl> 8.42, 8.42, 8.42, 8.25, 8.33, 8.33, 8.25, 8.50, 8.42, 8.42, 8.17, 8.17, 8.08, 8.00, 8.75, 8.00, 8.42, ... ## $ uniformity <dbl> 10.00, 10.00, 10.00, 10.00, 10.00, 10.00, 10.00, 10.00, 9.33, 10.00, 10.00, 10.00, 10.00, 10.00, 9.33,... ## $ clean_cup <dbl> 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10... ## $ sweetness <dbl> 10.00, 10.00, 10.00, 10.00, 10.00, 10.00, 10.00, 9.33, 9.33, 10.00, 10.00, 10.00, 10.00, 10.00, 9.33, ... ## $ cupper_points <dbl> 8.75, 8.58, 9.25, 8.67, 8.58, 8.33, 8.50, 9.00, 8.67, 8.50, 8.58, 8.50, 8.33, 8.58, 8.50, 8.17, 8.33, ... ## $ moisture <dbl> 0.12, 0.12, 0.00, 0.11, 0.12, 0.11, 0.11, 0.03, 0.03, 0.10, 0.10, 0.00, 0.00, 0.00, 0.05, 0.00, 0.03, ... ## $ category_one_defects <dbl> 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ... ## $ quakers <dbl> 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, ... ## $ color <chr> "Green", "Green", NA, "Green", "Green", "Bluish-Green", "Bluish-Green", NA, NA, "Green", NA, NA, NA, N... ## $ category_two_defects <dbl> 0, 1, 0, 2, 2, 1, 0, 0, 0, 4, 1, 0, 0, 2, 2, 0, 0, 2, 0, 8, 0, 2, 0, 0, 1, 2, 2, 1, 3, 0, 2, 1, 2, 0, ... ## $ expiration <chr> "April 3rd, 2016", "April 3rd, 2016", "May 31st, 2011", "March 25th, 2016", "April 3rd, 2016", "Septem... ## $ certification_body <chr> "METAD Agricultural Development plc", "METAD Agricultural Development plc", "Specialty Coffee Associat... ## $ certification_address <chr> "309fcf77415a3661ae83e027f7e5f05dad786e44", "309fcf77415a3661ae83e027f7e5f05dad786e44", "36d0d00a37243... ## $ certification_contact <chr> "19fef5a731de2db57d16da10287413f5f99bc2dd", "19fef5a731de2db57d16da10287413f5f99bc2dd", "0878a7d4b9d35... ## $ unit_of_measurement <chr> "m", "m", "m", "m", "m", "m", "m", "m", "m", "m", "m", "m", "m", "ft", "m", "m", "m", "m", "m", "m", "... ## $ altitude_low_meters <dbl> 1950.0, 1950.0, 1600.0, 1800.0, 1950.0, NA, NA, 1570.0, 1570.0, 1795.0, 1855.0, 1872.0, 1943.0, 609.6,... ## $ altitude_high_meters <dbl> 2200.0, 2200.0, 1800.0, 2200.0, 2200.0, NA, NA, 1700.0, 1700.0, 1850.0, 1955.0, 1872.0, 1943.0, 609.6,... ## $ altitude_mean_meters <dbl> 2075.0, 2075.0, 1700.0, 2000.0, 2075.0, NA, NA, 1635.0, 1635.0, 1822.5, 1905.0, 1872.0, 1943.0, 609.6,...
A quick glimpse of our data (no pun intended) is enough to indicate that our dataset is far from clean.
It also looks like there is missing data everywhere. Lets see how much.
Missing Data
library(naniar) vis_miss(coffee_ratings)
Thankfully, it’s not as bad as I thought it was going to be. For the nature of my question I am only going to using the total_cupper_points, country_of_origin, grading_date and species variables which all have little to no missing data (I thought this would be more of an issue, but looking back at it I’m thankful it isn’t for this case.)
Quantites of Coffee per Country
As stated in the description of our dataset (see the readme.md)
“These data were collected from the Coffee Quality Institute’s review pages in January 2018.”
(I am not sure how grammatical that phrase is but ok.)
To better understand our data, lets look at the frequencies of our data in terms of countries listed in our data set. Because there is only one instance of missing data, we will remove it from our plots for aesthetic reasons.
library(ggthemes)
# Need to make a new transformed dataset for this visualization
(
country_table<-coffee_ratings %>%
count(country_of_origin = factor(country_of_origin)) %>%
mutate(pct = prop.table(n)) %>%
arrange(-pct) %>%
tibble()
)
## # A tibble: 37 x 3
## country_of_origin n pct
## <fct> <int> <dbl>
## 1 Mexico 236 0.176
## 2 Colombia 183 0.137
## 3 Guatemala 181 0.135
## 4 Brazil 132 0.0986
## 5 Taiwan 75 0.0560
## 6 United States (Hawaii) 73 0.0545
## 7 Honduras 53 0.0396
## 8 Costa Rica 51 0.0381
## 9 Ethiopia 44 0.0329
## 10 Tanzania, United Republic Of 40 0.0299
## # ... with 27 more rows
# Together with my knowledge of ggplot and google, these visualizations became possible
ggplot(
country_table %>% filter(country_of_origin != "NA"),
mapping = aes(
x = reorder(country_of_origin, n),
y = pct,
group = 1,
label = scales::percent(pct)
)
) +
theme_fivethirtyeight() +
geom_bar(stat = "identity",
fill = "#634832") +
geom_text(position = position_dodge(width = 0.9),
# move to center of bars
hjust = -0.05,
#Have Text just above bars
size = 2.5) +
labs(x = "Country of Origin",
y = "Proportion of Dataset") +
theme(axis.text.x = element_text(
angle = 90,
vjust = 0.5,
hjust = 1
)) +
ggtitle("Country of Origin Listed in Coffee Ratings Dataset " ) + # This Emoji messes up this line in R markdown but hey, it
scale_y_continuous(labels = scales::percent) + # looks good.
coord_flip()
From a brief look at our table and bar chart we see that over 54% of our dataset consists of coffees from Mexico, Columbia, Guatemala and Brazil. But this only tells us part of the story, what species of coffees do we have in our dataset from each country?
Before looking at that lets look at the overall Arabica/Robusta proportion in our dataset:
# Need to make a new transformed dataset for this visualization
species_table<-coffee_ratings %>%
count(species = factor(species)) %>%
mutate(pct = prop.table(n)) %>% tibble()
ggplot(species_table,mapping=aes(x=species,y=pct,group=1,label=scales::percent(pct)))+
theme_fivethirtyeight()+
geom_bar(stat="identity",
fill=c("#634832","#3b2f2f"))+
geom_text(position = position_dodge(width=0.9), # move to center of bars
vjust=-0.5, #Have Text just above bars
size = 3)+
scale_y_continuous(labels = scales::percent)+
ggtitle("Arabica vs Robusta Proportion in Dataset ")
Wow! only 2% of Coffee in our dataset is from Robusta beans! But if you think about this in context, this shouldn’t be too much of a suprise. Robusta coffee is primarily used in instant coffee,espresso and filler for coffee blends. The reason why Robusta coffee beans are not graded proportionately as Arabica beans are is due to the fact that the quality of these bitter, earthy beans are usually not as desirable to coffee drinkers as their smoother, richer Arabica counterparts.
With that in mind, lets see how the breakdown proportionally per country:
# Need to make a new transformed datasets for this visualization
(
arabica_countries<-coffee_ratings %>%
filter(species =="Arabica") %>%
count(species=factor(species),
country=country_of_origin) %>%
mutate(pct = prop.table(n)) %>%
arrange(-n) %>%
tibble()
)
## # A tibble: 37 x 4
## species country n pct
## <fct> <chr> <int> <dbl>
## 1 Arabica Mexico 236 0.180
## 2 Arabica Colombia 183 0.140
## 3 Arabica Guatemala 181 0.138
## 4 Arabica Brazil 132 0.101
## 5 Arabica Taiwan 75 0.0572
## 6 Arabica United States (Hawaii) 73 0.0557
## 7 Arabica Honduras 53 0.0404
## 8 Arabica Costa Rica 51 0.0389
## 9 Arabica Ethiopia 44 0.0336
## 10 Arabica Tanzania, United Republic Of 40 0.0305
## # ... with 27 more rows
ggplot(arabica_countries %>% filter(country!="NA"),
mapping=aes(x=reorder(country,n),y=pct,group=1,label=scales::percent(pct))) +
theme_fivethirtyeight()+
geom_bar(stat="identity",
fill="#634832")+
geom_text(position = position_dodge(width = 0.9),
# move to center of bars
hjust = -0.05,
#Have Text just above bars
size = 2.5) +
ggtitle("Arabica Coffee Countries (for our dataset) ") +
scale_y_continuous(labels = scales::percent) +
coord_flip()
(
robusta_countries<-coffee_ratings %>%
filter(species =="Robusta") %>%
count(species = factor(species),
country=country_of_origin) %>%
mutate(pct = prop.table(n)) %>%
arrange(-n) %>%
tibble()
)
## # A tibble: 5 x 4
## species country n pct
## <fct> <chr> <int> <dbl>
## 1 Robusta India 13 0.464
## 2 Robusta Uganda 10 0.357
## 3 Robusta Ecuador 2 0.0714
## 4 Robusta United States 2 0.0714
## 5 Robusta Vietnam 1 0.0357
ggplot(robusta_countries %>% filter(country!="NA"),
mapping=aes(x=reorder(country,n),y=pct,group=1,label=scales::percent(pct))) +
theme_fivethirtyeight()+
geom_bar(stat="identity",
fill="#3b2f2f")+
geom_text(position = position_dodge(width = 0.9),
# move to center of bars
hjust = -0.05,
#Have Text just above bars
size = 2.5) +
ggtitle("Robusta Coffee Countries (for our dataset) ") +
scale_y_continuous(labels = scales::percent) +
coord_flip()
The Robusta coffees that we have in this dataset are mostly from India and Uganda, with a few coffees from the Ecuador, the United States and Vietnam. With that being known, Lets look at the Arabica/Robusta ratio for countries that we have Robusta Data on.
coffee_ratings %>%
filter(country_of_origin %in% c("India","Uganda","Ecuador","United States","Vietnam")) %>%
count(country_of_origin,species) %>%
group_by(country_of_origin)
## # A tibble: 10 x 3
## # Groups: country_of_origin [5]
## country_of_origin species n
## <chr> <chr> <int>
## 1 Ecuador Arabica 1
## 2 Ecuador Robusta 2
## 3 India Arabica 1
## 4 India Robusta 13
## 5 Uganda Arabica 26
## 6 Uganda Robusta 10
## 7 United States Arabica 8
## 8 United States Robusta 2
## 9 Vietnam Arabica 7
## 10 Vietnam Robusta 1
ggplot(coffee_ratings %>% filter(country_of_origin %in% c("India","Uganda","Ecuador","United States","Vietnam")),
mapping=aes(x=country_of_origin,fill=species))+
theme_fivethirtyeight()+
geom_bar(position="fill")+
scale_fill_manual(values=c("#BE9B7B", "#3b2f2f"))+
theme(legend.title = element_blank())+
ggtitle("Arabica/Robusta Ratio from countries with Robusta data ")
Now that we have better understanding of where our coffees come from, we can get into trying to answer the question of where the best coffee beans are in the world.
Well, it depends.
What type? What year?
It would be nice to just pick out the highest rated coffee and be done with it, but that wouldn’t tell us anything (or really motivate a blog post). We need to consider is when was a given coffee graded. That can tell us the performance of a given country’s over time. Additionally, we need to consider the species of bean- where is the best ranked Arabica coffee from? Where is the best Robusta coffee from?
Before we can answer this question, we need to clean the grading_date and convert them into the date data from. Thankfully, the lubridate package will help us with doing this relatively easy. After that we will formulate our data set with the dplyr package to get the data in the form we need for our visualization.
|
library(lubridate)
# Getting the year data
coffee_ratings$new_dates<-coffee_ratings$grading_date %>% mdy()
coffee_ratings$score_year<- coffee_ratings$new_dates %>% year()
# Dataset for visualizations
(
top_annual_score<- coffee_ratings %>%
group_by(species,
score_year,
country_of_origin) %>%
summarise(max_points = max(total_cup_points)) %>%
filter(max_points == max(max_points)) %>%
arrange(-max_points)
)
## # A tibble: 15 x 4
## # Groups: species, score_year [15]
## species score_year country_of_origin max_points
## <chr> <dbl> <chr> <dbl>
## 1 Arabica 2015 Ethiopia 90.6
## 2 Arabica 2010 Guatemala 89.8
## 3 Arabica 2013 Brazil 88.8
## 4 Arabica 2012 Peru 88.8
## 5 Arabica 2016 China 87.2
## 6 Arabica 2014 Costa Rica 87.2
## 7 Arabica 2011 Brazil 86.9
## 8 Arabica 2017 Honduras 86.7
## 9 Arabica 2018 Kenya 84.6
## 10 Robusta 2014 Uganda 83.8
## 11 Robusta 2017 India 83.5
## 12 Robusta 2015 India 83.2
## 13 Robusta 2012 India 82.8
## 14 Robusta 2016 India 82.5
## 15 Robusta 2013 India 81.2
ggplot(top_annual_score,
mapping=aes(x=score_year,
y=max_points,
label=paste0(score_year,"\n",country_of_origin,"\n", max_points),
color=country_of_origin))+
theme_fivethirtyeight()+
geom_text(position = position_dodge(width = 0.9),
# move to center of bars
hjust =-0.2,
#Have Text just above bars
size =3.5) +
geom_point(size=4,
alpha=0.8)+
theme(legend.position = "none")+
facet_wrap(~species)+
ggtitle(" Top Scoring Coffees by Year - Faceted on Species ")
From our visualization and table we see for Arabica beans, the top coffee varied from country to country for a given year. However for Robusta, India seemed to have dominated with consistent wins from 2012 – 2017 with an exception of Uganda beating them in 2014.
Overall, for our given timespan in our dataset, for Arabica beans (as well as our entire dataset) Ethiopia scored the highest with a score of 90.58 and for Robusta Beans Uganda had the highest score of 83.75.
The overall summary for of scores for Arabica and Robusta beans accross the years is plotted in the below visualization with boxplots.
(arabica_robusta_average_score<-
coffee_ratings %>%
group_by(species) %>%
summarise(average_score = mean(total_cup_points),
lower_ci = mean(total_cup_points) - 1.96*sqrt(var(total_cup_points)/length(total_cup_points)),
upper_ci = mean(total_cup_points) + 1.96*sqrt(var(total_cup_points)/length(total_cup_points)))
)
## # A tibble: 2 x 4
## species average_score lower_ci upper_ci
## <chr> <dbl> <dbl> <dbl>
## 1 Arabica 82.1 81.9 82.3
## 2 Robusta 80.9 80.0 81.8
ggplot(coffee_ratings,mapping=aes(x=score_year,y=total_cup_points,group=score_year))+
theme_fivethirtyeight()+
geom_boxplot(color="#3b2f2f")+
coord_flip()+
facet_wrap(~species)+
geom_hline(data=arabica_robusta_average_score,
mapping=aes(yintercept=average_score),
size= 0.5)+
geom_hline(data=arabica_robusta_average_score,
mapping=aes(yintercept=lower_ci),
linetype="dashed",
size= 0.5)+
geom_hline(data=arabica_robusta_average_score,
mapping=aes(yintercept=upper_ci),
linetype="dashed",
size= 0.5)+
ggtitle("Boxplots of Arabica and Robusta Beans from 2010-2018 \n
with confidence intervals plotted")
Besides for some outliers on the lower end of the scoring range, most of these coffees in this dataset are on average score around 80 or above. What can be implied from here is that the coffees that come in to be graded by the Coffee Quality Institute are usually those which have are assumed to be high in quality. This shouldn’t be a surprise because it appears that beans graded by the CQI are usually those which are submitted as it says it on the site’s banner
Welcome to the Coffee Quality Institute (CQI) database, which allows users to submit a sample for Q Grading …
Conclusion
Its not surprising for our data set that Robusta beans scored poorer than their Arabica counterparts. That is something that anyone with some background in coffee will tell you- Arabica is generally more desirable by coffee drinkers and Robusta is usually used for instant coffee, Espresso and filler for coffee blends.
What is more telling about this dataset is that the best coffee is not something which is country specific for Arabica beans. However for Robusta beans, India and Uganda being top annual scorers in this domain seems to be indicative of higher quality Robusta in these countries.
Additionally, based on the fact that the average score for both Arabica and Robusta Beans is in the 80 range is telling that the beans which are being graded are those with a assumed to possess higher quality are submitted to be graded. Does this mean we have a overarching view of the worldwide coffee quality range? Certainly not.
But it could be telling on what quality of coffee you’re having the next time you visit a coffee shop which has coffee which is graded by the CQI.
(Let me know how it tastes!)
Thanks for reading!
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