Guidelines and submission instructions:

●   I suggest working in groups of 1-4 students. You can form teams in the google sheet                                                          https://docs.google.com/spreadsheets/d/1cXB6JAbB_dARXHWa6t7O4e-dvv-0Hl-5Ne9UDmj_hAI/edit?usp=sharing . It would be great that in each team there is a student who has prior python experience.

●   If you work on the assignment individually or in a team, you will need to submit your python notebook that contains         answers to all questions. People working in a team can submit the same file and it's allowed to have an identical notebook. Please indicate your group number and provide all of your teammates names.

●   To answer some questions, you will need to write code, interpret results, etc. All answers should be included in your python notebook.

Questions:

1.   What does "counterfactual" mean and what are three insights you gained from watching the video "Time, Interrupted: Measuring Intervention Effects with Interrupted Time-Series Analysis" at the following link: https://youtu.be/uuo8SwA1HO8?

Case 1: Global warming

The Nenana Ice Classic (https://en.wikipedia.org/wiki/Nenana_Ice_Classic) is an annual event held in Nenana, Alaska, in  which individuals attempt to guess the exact time that the ice on the Tanana River will break up. The event serves as a        fundraiser and is a beloved guessing game among Alaskans. It has been held annually since 1917, when workers building a bridge across the Tanana River near Nenana were unable to begin their work due to the frozen river. To pass the time, the   workers began betting on when the ice would break up. A large tripod was erected on the ice, and it was decided that whe  the ice began to break up and the tripod moved a certain distance downstream, that would be the official time of the            breakup. The winner of the bet was the person who guessed closest to the actual time. Every year since then, the same        routine has been followed, and the betting has grown more intense. The tripod is connected to an official clock via a rope,  and the clock is tripped to stop when the rope is extended by the tripod floating downstream. The official time of the ice     breaking is recorded and made available on the Nenana Ice Classic website (https://www.nenanaakiceclassic.com/).

In addition to its entertainment value, the Nenana Ice Classic data also has ecological significance. By analyzing the ice breaking times over the years, we can examine whether the ice is breaking up earlier each year, which would provide    evidence of global warming. Some believe that global warming began in 1960, and therefore the data collected by the   Nenana Ice Classic can provide valuable insights into the impact of global warming on natural phenomena.

Data:

The data in Nenana1.txt and Nenana2.txt (I downloaded the data for you from the NSIDC website:                            https://nsidc.org/data/nsidc-0064 ) were popularized in the October 26, 2001 issue of Science in an article by         Stanford professors Raphael Sagarin and Fiorenza Micheli. (If in case you are not familiar: Science publishes only the very best peer-reviewed and the most cited science research articles in the world)

2.    Import the data from Nenana1.csv in python and call it df.

https://raw.githubusercontent.com/robertasgabrys/Forecasting/main/Nenana1.csv

3.    (we will work on this task in class) Create a KPI (key performance indicator) to assess the global warming hypothesis by measuring the amount of time in days between the moment the ice breaks in Nenana (as         recorded in the Nenana Ice Classic contest) and January 1st of each year.

4.   Create a line graph utilizing the KPI defined as the amount of time in days between the moment ice breaks in Nenana and January 1 of each year. Additionally, include a vertical line to represent the hypothesized    year of global warming, 1960, and create separate regression lines for data prior to and after 1960. What    information can be inferred from this graph?