Cynthia Njau

Cynthia_Njau TODO.md

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+# TODO
+> Edit this file to add your answeres to each TODO item. Its okay to link to external documentation as well, just remember to ensure that our reviewers has access.
+> When you're ready to submit, click **Commit changes...** and save your responses to a new branch titled 'implementation' and create a pull request.
+
+>Before you start reading, please configure your environment as described in the "Before you get started" README section of your GitHub repository.*
+
+In this task, you will work with the [Chicago Crime Dataset](https://console.cloud.google.com/marketplace/product/city-of-chicago-public-data/chicago-crime) to figure out some insights regarding the crimes commited in Chicago.
+
+Here are some examples of the columns you will work with:
+
+|Variable|Description|
+|----:|-----|
+|primary_type |What type of crime was committed|
+|location_description |Description of the location where the crime was committed|
+|arrest|If the crime led to an arrest or not|
+
+Feel free to explore the dataset and try out different queries using the BigQuery interface.
+Once you have a query that answers the question, add the code snippet to the specific question as well any supportive reasoning/comment that you may have.  
+
+## Task 1 
+
+From what date is the oldest data point in the data set? 
+
+> TODO: 2001-01-01 01:00:00 UTC
+SELECT distinct 
+date
+FROM `bigquery-public-data.chicago_crime.crime` 
+order by date 
+
+LIMIT 1000;
+
+## Task 2
+
+Which year had the largest amount of crimes and how many crimes were committed that year?
+
+> TODO: The year is 2002 and the number of crimes is 486815
+SELECT
+year,
+COUNT(unique_key) as Number_of_crimes
+FROM `bigquery-public-data.chicago_crime.crime` 
+group by 1
+order by 2 desc
+
+
+## Task 3
+
+Let's define "Arrest Rate" as the share of crimes that led to an arrest.
+What were the five most common crimes in 2020? Which of those has the highest and lowest arrest rate?
+
+> TODO: The five most common crimes were : BATTERY,THEFT,CRIMINAL DAMAGE,DECEPTIVE PRACTICE and ASSAULT.
+The highest is BATTERY with a arrest rate of 16.66% and the lowest is DECEPTIVE PRACTICE with an arrest rate of 2.1%.
+
+SELECT primary_type,
+       COUNT(*) AS total_crimes,
+       SUM(CASE WHEN arrest = true THEN 1 ELSE 0 END) AS total_arrests,
+       SUM(CASE WHEN arrest = true THEN 1 ELSE 0 END) / COUNT(*) AS arrest_rate
+FROM `bigquery-public-data.chicago_crime.crime`
+WHERE year = 2020
+GROUP BY primary_type
+ORDER BY 2 
+DESC
+LIMIT 5;
+
+
+
+## Task 4
+
+What year had the highest arrest rate? Plot the number of crimes per year and comment on the trend.
+
+> TODO: The year with the highest arrest rate is 2005 with a rate of 31.06%.
+ The link to the plot :
+ https://docs.google.com/spreadsheets/d/1gIJozo0uMOimKvFI8jvuqzgff7FE-B4Ni5mpLkek-O4/edit?usp=sharing
+COMMENT ON THE PLOT: As the years increase, we can see the crime rate is reducing.
+SQL QUERY : SELECT year,
+       COUNT(*) AS total_crimes,
+       SUM(CASE WHEN arrest = true THEN 1 ELSE 0 END) AS total_arrests,
+       SUM(CASE WHEN arrest = true THEN 1 ELSE 0 END) / COUNT(*) AS arrest_rate
+FROM `bigquery-public-data.chicago_crime.crime`
+
+GROUP BY year
+ORDER BY 4 DESC
+;
+
+
+
+## Task 5
+
+Which year had the most number of crimes leading to an arrest? How many arrests were made during that year? Plot the trend for total number of arrests per year.
+
+> TODO: The year that had the most number of crimes leading to an arrest is 2005 having 140925 arrests.
+
+SQL QUERRY:SELECT year,
+       COUNT(*) AS total_crimes,
+       SUM(CASE WHEN arrest = true THEN 1 ELSE 0 END) AS total_arrests,
+       SUM(CASE WHEN arrest = true THEN 1 ELSE 0 END) / COUNT(*) AS arrest_rate
+FROM `bigquery-public-data.chicago_crime.crime`
+
+GROUP BY year
+ORDER BY 4 DESC
+;
+PLOT LINK:https://docs.google.com/spreadsheets/d/1A638iBcr0STpDXC-Q5uKQJAXS78MrMrXggzSLf2Z6Sc/edit?usp=sharing
+COMMENT ON PLOT: Over the years, there has been a  decrease in the total number of arrests, indicating a potential shift in law enforcement strategies or societal norms regarding crime.
+
+## Task 6
+
+How has the arrest rate looked like over time? 
+- Plot the trend of the arrest rate.
+- Between which years can you see the biggest change in "Arrest Rate"?
+- Can you point at specific reasons to why the Arrest Rate dropped between those years? Comment on your conclusions.
+
+> Since the data set is constantly updating, disregard the year 2021 and later for the analysis in this question.
+
+> TODO: 
+PLOT LINK:https://docs.google.com/spreadsheets/d/1bfqgvLitZ9v_yuB8Tcqi7n7gMstBG5V2uAb_kZkZdpg/edit?usp=sharing
+
+The years you can see a big change is from 2015 to 2016.
+Between 2015 and 2016, there was a decrease in total crimes and total arrests in Chicago. However, while the total number of crimes decreased, there was a more significant decrease in total arrests , leading to an apparent drop in the arrest rate from 26.45% in 2015 to 19.65% in 2016. Some of the factors that may have caused this change are :changes in law enforcement strategies, policies and crime patterns.