Average_Transaction_Value_Stats

Average Transaction Value Stats — dabstep Dataset

Dataset Overview

payments.csv is the primary dataset. Key columns:

• merchant: Merchant name (e.g., Crossfit_Hanna, Belles_cookbook_store, Golfclub_Baron_Friso, Martinis_Fine_Steakhouse, Rafa_AI)
• card_scheme: Payment network (e.g., NexPay, GlobalCard, SwiftCharge, TransactPlus)
• year: Transaction year (all data is 2023)
• day_of_year: Day 1–365 (no date column — months must be derived from this)
• eur_amount: Transaction amount in euros
• shopper_interaction: Ecommerce or POS
• issuing_country: Card-issuing country code (SE, NL, LU, IT, BE, FR, GR, ES)
• acquirer_country: Acquiring bank country code
• aci: Authorization Characteristics Indicator (A–G)
• email_address: Hashed shopper email (can be NaN)

Critical: Apply ALL Filters Specified in the Question

When a question says "merchant X's card_scheme Y transactions", filter by BOTH merchant AND card_scheme. Forgetting one filter is the most common error.

df_filtered = df[
    (df['merchant'] == 'Merchant_Name') &
    (df['card_scheme'] == 'SchemeName') &
    (df['day_of_year'] >= start_day) &
    (df['day_of_year'] <= end_day)
]

Month → day_of_year Conversion (2023, non-leap year)

Use the start of the first month and end of the last month as inclusive bounds.

Standard Analysis Pattern

import pandas as pd

df = pd.read_csv('/path/to/payments.csv')

# Step 1: Apply all filters
df_filtered = df[
    (df['merchant'] == 'Merchant_Name') &       # if specified
    (df['card_scheme'] == 'SchemeName') &         # if specified
    (df['day_of_year'] >= START_DAY) &            # if date range given
    (df['day_of_year'] <= END_DAY)
]

# Step 2: Group and compute mean
result = (
    df_filtered
    .groupby('grouping_column')['eur_amount']
    .mean()
    .round(2)
    .sort_values(ascending=True)  # always ascending unless stated otherwise
)

# Step 3: Format output
answer = [f"{k}: {v:.2f}" for k, v in result.items()]

Output Format

The required format [grouping_i: amount_i, ] means a Python list of strings:

['BE: 86.39', 'SE: 91.89', 'ES: 92.83', ...]

• Each element: "GROUPING_VALUE: AMOUNT" (colon-space separator)
• When grouping by country: use the country code
• Amounts rounded to 2 decimal places (e.g., 101.00 not 101.0)
• Sorted in ascending order by amount

Do NOT return tuples like [('BE', 86.39), ...].

Special Case: "Average per Unique X"

When the question says "average transaction amount per unique email" (or per unique card, etc.):

# Correct: mean of per-group means
per_group_mean = df.groupby('email_address')['eur_amount'].mean()
answer = round(per_group_mean.mean(), 3)

This is NOT total_amount / count_unique_emails. The correct interpretation is:

1. For each unique email, compute their average transaction amount
2. Take the average of those per-email averages

Validation Checklist

Before submitting your answer:

1. Did you filter by all criteria mentioned (merchant, card_scheme, date range)?
2. Did you use the correct day_of_year bounds for the requested months?
3. Is the output sorted ascending by amount?
4. Are amounts rounded to 2 decimal places and formatted as strings with :?
5. For "per unique X" questions: did you use mean-of-means, not total/count?