Merge remote-tracking branch 'origin/master'

Naive analysis.md

@@ -22,7 +22,7 @@ We investigate the average rating that EU and NA users give for each ABV rounded
 
 We also want to investigate if the number of ratings per rounded ABV percentage has to do something with the average rating per ABV?
 
-![Count beers with certain ABV](./plots/count_abv.png)
+![Count beers with certain ABV](./plots/abv_distribution.png)
 
 > **Insight:**
 > Beers with ABV lower than 5% or greater than 15% have fewer numbers of ratings. If only a few users rated and graded them well, this results in a better average rating for the specific ABV.

README.md

@@ -5,13 +5,13 @@ the World’s Most Beloved Drink
 
 It is accepted worldwide that **beer** is the "most beloved drink", but who is leading the competition? 
 
-We would say Europe and America are the biggest beer consumers among all continents.
+We would say Europe and North America are the biggest beer consumers among all continents.
 
-But again, do Americans and Europeans drink the same beer types, or is there a beer attribute that makes a difference between this two big consumer groups?
+But again, do Americans and Europeans drink the same beer types, or is there a beer attribute that makes a difference between these two big consumer groups?
 #### Let's investigate the beer preferences across the Atlantic!
 
 ## Description
-Using a large dataset, which provides beer ratings and reviews on beers from people all around the world, we will investigate the difference in beer preferences across Americans and Europeans, and try to find the reason behind it! Embracing the 14 beer general styles provided, which differ in characteristics as ABV, we expect to find interesting results. 
+Using a large dataset, which provides beer ratings and reviews on beers from people all around the world, we will investigate the difference in beer preferences across Americans and Europeans, and try to find the reason behind it! Embracing 14 different beer styles, which differ in characteristics as ABV, we expect to find interesting results. 
 
 We suspect that cultural dissimilarities among these two groups might lead to different inclinations when it comes to alcohol concentration in beers. Moreover, we will inspect the correlation of beer type with this inclination and we will deep into the evolution of the beer preferences between 2000 and 2017, hoping to find differences between America and Europe.
 

seasonality_nd.md

@@ -0,0 +1,68 @@
+---
+layout: default
+---
+
+# Seasonality
+
+---
+
+## Why is there a seasonality trend between Europe and North America?
+
+We will try to answer this question by first decomposing the time series for each region into seasonality and trend.
+
+![Seasonality; NA vs EU](./plots/seasonality_na_vs_eu.png)
+
+From the graph above, we can conclude the following points:
+
+- Both regions show a clear seasonality pattern. However, in Europe, there is more noise present, and there is a second peak, which seems to appear in spring. What could be the reason for this?
+- The trend seems to be linearly increasing for both continents with a similar slope. Although North America definitely shows higher ABV on average at all times!
+
+---
+
+### Question: What are the suspects which are the reason for seasonality?
+
+### Oktoberfest <sup>Suspect 1</sup>
+
+We suspect that the difference in the seasonality pattern of American and European ratings might be due to significant beer events that take place in Europe, such as **Oktoberfest**, which is, in fact, the world's largest beer festival and takes place in late September and the first weekend of October.
+
+### Fresh and light during Summertime <sup>Suspect 2</sup>
+
+Have you ever relaxed at a beach in summer, with your sun glasses on, sipping gently on your 12% Russian Imperial stout? Yes... Me neither. We suspect that people tend to drink lighter beers overall during hot summer days and rather prefer stronger kinds of beer during the colder parts of the year. This does not seem too unlikely, given that the seasonality pattern in both continents show higher ABV during winter periods on average than during summer!
+
+To be sure, we will take a closer look at the trend and the seasonality (including residuals):
+
+![Seasonality](./plots/seasonality.png)
+
+_When keeping the residuals, the second peak in Europe looks more like a plateau during springtime, where North America seems to drop more quickly._ 
+
+### St. Patrick's Day <sup>Suspect 3</sup>
+
+<div style="display: flex; align-items: center; margin-top: 15px;">
+    <div style="flex: 1;">
+        <b>Have you ever heard of St. Patrick's Day?</b>
+        <br><br>
+        - It is an Irish traditional holiday, taking place in March.
+        This might be the reason for the second peak appearing in spring!
+    </div>
+    <div style="flex-shrink: 0; margin-left: 20px;">
+        <img src="./gifs/stpatrick.gif" width="130" height="130" alt="St. Patrick">
+    </div>
+</div>
+
+Since Guinness, and stouts in general, are rather on the strong side of beer spectrum, an increase in consumption could easily spark a peak in the ABV pattern.
+
+In very a simple approach to investigate this, we decided to decompose the seasonality of each beer style into Fourier modes by running a simple discrete Fourier transform over it. Naturally converting from frequency space to periodicity space allows to easily filter beer styles that show a significant mode corresponding to a 12-month period. Comparing the amplitudes, and accounting in the popularity of the beer style in addition to extracting the phase shift of the peaks allows us to gain deeper insight on what the seasonality is composed of. The result is shown below
+<br>
+
+<iframe width="800" height="600" frameborder="0" seamless="seamless" scrolling="no" src="./plots/html/peak_seasonality.html"></iframe>
+
+<br>
+
+There are a few observations we make from this:
+- Multiple beer styles show seasonal variation, most notably in both continents are... specialty beers.. They are truly special
+- In both continents, as we suspected early on, a lot of styles contribute to seasonality with peak ABV values in Winter. This accounts for a whopping $\sim 80$% of the seasonality in North America and around $65$% in Europe.
+- We even can confirm our first suspect! **Oktoberfest** shows its face (or peak) on both continents each October in the form of a contribution from Dark Lagers, which contains among others **Märzen** as well as **Oktoberfestbeer**! Although the overall contribution to the total is only $\sim 5$
+- We also observe styles such as IPA, which showed marginal seasonality overall to have a larger contribution in America and pretty much none in Europe. We can recall here that due to the huge popularity in North America, even a slight seasonal change in ABV can have a strong overall effect if enough people drink (and rate) it.
+- To our disappointment, St. Patricksday could not be confirmed. We observe the second peak in May, which is too late, and in the form of **Strong Ales** and **Porters** which peak only in Europe each year, a group of rather strong beers seems to gain popularity each May of every year. 
+
+**Note:** Maybe looking at the seasonality of beer styles will help us understand its cause better? -> [Beer style seasonality](/ada-welovepandas-webpage/Beer%20style%20seasonality)