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What is Cohort Analysis and How does It Works?

In the fast-paced world of data analytics, extracting actionable insights is crucial for informed decision-making. Cohort Analysis stands as a powerful tool in this realm, providing a nuanced understanding of user behavior over time.

This article aims to demystify Cohort Analysis, elucidating its significance and demonstrating how it effectively groups data by specific characteristics.



What is Cohort Analysis?

Cohort Analysis is a method of grouping and analyzing data based on specific characteristics shared by a set of individuals. These characteristics could include the time of acquisition, geographic location, or any other defining attribute. This method is widely used in various fields, including business, marketing, and healthcare.



Why use Cohort Analysis?

Types of Cohort Analysis

How does cohort analysis work?

Importance of Cohort Analysis

Cohort analysis is very much important and crucial because it helps to identify the required patterns, trends, and changes in user behavior over time. Cohort analysis is used by most of the businesses for the reasons listed below, which highlights its significance to overcome the overall processes:

Examples of Cohort Analysis

Steps to Conduct Cohort Analysis

Step 1: Define Cohorts:

Start by determining the criteria for cohort creation. This could be the month of user acquisition, the source of acquisition, or any other relevant characteristic.

Step 2: Data Collection:

Gather comprehensive data on user behavior, ensuring it aligns with the chosen cohort criteria. This data may encompass metrics like user engagement, retention, or conversion rates.

Step 3: Create Cohort Grid:

Organize the data into a cohort grid, where each row represents a cohort and each column signifies a specific time period (e.g., weeks or months).

Step 4: Calculate Metrics:

Compute key metrics for each cohort over time. Common metrics include retention rates, conversion rates, and average revenue per user.

Step 5: Visualize Results:

Utilize charts and graphs to visualize cohort trends. This aids in easily identifying patterns, such as whether certain cohorts exhibit higher or lower engagement over time.

Python Implementation – Cohort Analysis

Import the necessary Libraries

At first we will import the libraries that we will be using.




import pandas as pd
import seaborn as sns
import matplotlib.pyplot as plt

Load the datasetT

he next step is to load inbuilt dataset. Use load_dataset from seaborn library to load the dataset.




# Load the Titanic dataset
titanic_df = sns.load_dataset('titanic')
titanic_df.head()

Output:

    survived    pclass    sex    age    sibsp    parch    fare    embarked    class    who    adult_male    deck    embark_town    alive    alone
0 0 3 male 22.0 1 0 7.2500 S Third man True NaN Southampton no False
1 1 1 female 38.0 1 0 71.2833 C First woman False C Cherbourg yes False
2 1 3 female 26.0 0 0 7.9250 S Third woman False NaN Southampton yes True
3 1 1 female 35.0 1 0 53.1000 S First woman False C Southampton yes False
4 0 3 male 35.0 0 0 8.0500 S Third man True NaN Southampton no True

Data Cleaning

From the dataset we can see that there are some missing values, so we are dropping the missing values from specific columns.




titanic_df.isna().sum()
# Drop missing values
titanic_df = titanic_df.dropna(subset=['embarked', 'age','deck'])
titanic_df.isna().sum()

Output:

survived       0
pclass 0
sex 0
age 0
sibsp 0
parch 0
fare 0
embarked 0
class 0
who 0
adult_male 0
deck 0
embark_town 0
alive 0
alone 0
dtype: int64

Since, cohort analysis involves grouping individuals based on shared characteristics or experiences over time. In this case, the “embarked” values are being used to create cohorts, which are subsets of the data based on a common attribute. Before moving forward let’s change the data type of age into integer making it easier to categorize and analyze cohorts.




titanic_df['age'] = titanic_df['age'].astype(int)

Cohort Analysis

Now, let’s define bins and labels:

The code is creating a new column in the DataFrame called age_cohorts based on the values in the existing age column. This step is performed for the purpose of binning or categorizing age values into specific ranges or cohorts.




# Create cohorts based on age ranges
bins = [0, 10, 20, 30, 40, 50, 60, 70, 80]
labels = ['0-10', '11-20', '21-30', '31-40',
          '41-50', '51-60', '61-70', '71-80']
titanic_df['age_cohorts'] = pd.cut(
    titanic_df['age'], bins=bins, labels=labels, right=False)
titanic_df['age_cohorts'].head()

Output:

1     31-40
3 31-40
6 51-60
10 0-10
11 51-60
Name: age_cohorts, dtype: category
Categories (8, object): ['0-10' < '11-20' < '21-30' < '31-40' < '41-50' < '51-60' < '61-70' < '71-80']

Next step is Grouping and Aggregation:

Grouping the data in the DataFrame titanic_df by two columns: ‘cohorts’ and ‘age_cohorts’. Then, Selection of ‘survived’ column within each group. At last, calculation of mean survival for each group.

The next line pivots the data for better visualization. It takes the DataFrame cohort_survival and creates a pivot table where the rows correspond to the unique values of ‘cohorts’, the columns correspond to the unique values of ‘age_cohorts’, and the values within the table are the survival rates.




# Calculate survival rates within each cohort
cohort_survival = titanic_df.groupby(['embarked', 'age_cohorts'])[
    'survived'].mean().reset_index()
# Pivot the data for better visualization
cohort_survival_pivot = cohort_survival.pivot(
    'embarked', 'age_cohorts', 'survived')
cohort_survival_mean_imputed = cohort_survival_pivot.fillna(
    cohort_survival_pivot.mean())
print(cohort_survival_mean_imputed)

Output:

age_cohorts  0-10     11-20    21-30     31-40     41-50     51-60     61-70  \
embarked
C 0.8 0.857143 0.81250 0.733333 0.833333 0.545455 0.666667
Q 0.8 0.803571 0.75625 1.000000 0.000000 0.541958 0.416667
S 0.8 0.750000 0.70000 0.757576 0.473684 0.538462 0.166667

age_cohorts 71-80
embarked
C 0.0
Q 0.0
S 0.0

Visualize the Results

The final visualization code is here.




# Plot the cohort analysis
plt.figure(figsize=(12, 8))
sns.heatmap(cohort_survival_mean_imputed, annot=True, cmap='Blues', fmt=".2%")
plt.title('Cohort Analysis on Titanic Dataset')
plt.xlabel('Age Cohorts')
plt.ylabel('Embarked Cohorts')
plt.show()

Output:

Cohort Analysis

Benefits of Cohort Analysis

Challenges in Cohort Analysis

Conclusion

In the dynamic landscape of data analytics, Cohort Analysis emerges as a pivotal tool for unraveling actionable insights crucial for informed decision-making.

Cohort Analysis- FAQs

Can Cohort Analysis be applied to any type of business?

Yes, Cohort Analysis is versatile and can be applied across various industries, including e-commerce, SaaS, and mobile apps.

Are there tools available to facilitate Cohort Analysis?

Absolutely. Many analytics platforms and tools, such as Google Analytics and Mixpanel, offer features specifically designed for Cohort Analysis.

How often should Cohort Analysis be conducted?

The frequency depends on the business objectives. It can be done weekly, monthly, or based on specific milestones. Regular analysis helps in tracking changes and optimizing strategies accordingly.


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