YourPaceAI — From a dataset to a useful answer
Practice workbook · 2026-10-v1

FICTIONAL SALES CSV
id,day,category,sales_gbp
1,Mon,Books,40
2,Tue,Books,60
2,Tue,Books,60
3,Wed,Books,
4,Thu,Books,80
5,Fri,Books,100

Question: What is the average sales value across unique records with a recorded amount?
Unit: GBP. Blank means missing, not zero. Repeated id 2 is an exact duplicate. No population sampling claim is made.

PROJECT: A reproducible data analysis
Clean the fictional CSV, calculate the mean, design a chart and explain what the data cannot show.

1. Question, column meanings and cleaning rules
[Write your evidence here]

2. Clean values, formula or code, count and mean
[Write your evidence here]

3. Chart description and evidence-backed finding
[Write your evidence here]

4. Missing-data limits and a leakage-free evaluation plan
[Write your evidence here]

RUBRIC
- The raw data and stated cleaning rules are retained.
- The exact duplicate is handled and the missing amount is not silently replaced with zero.
- The mean is reproducible and chart units are clear.
- Findings do not claim causation or population generality.

The portfolio is a self-recorded learning artifact. Automatic assessment checks knowledge and applied scenario decisions, not the quality of this free-text workbook.