Mostafizur RahmanServices / Data Cleaning & Preparation
Data Cleaning & Preparation
Consistent, trustworthy data to build every report and model on.
- Data Cleaning
- Data Transformation
- Data Validation
- Data Quality Checks
- Python
- Pandas
- SQL
- Excel
- Power Query
Final pricing depends on data volume, complexity, and agreed deliverables.
Discuss your projectService overview
The problem, and what you gain
The problem it solves
Reports built on inconsistent spreadsheets, duplicated records and mismatched sources are slow to produce and hard to trust. Hours go into fixing the same data by hand every reporting cycle.
The value to you
You receive a clean, consistent dataset and a written record of every rule applied, so analysis and reporting start from a foundation your whole team can rely on.
Scope of work
What this service covers
- Profiling of missing values, duplicates, data types and outliers
- Standardising dates, categories, text and units
- Merging and reconciling multiple sources
- Handling anomalies with documented rules
- Validating the cleaned output against the source
- Full documentation of every transformation
My process
How the work runs
Review
We go through the files, the business context and what the data must support.
Profile
Missing values, duplicates, types, ranges and outliers are measured and summarised.
Clean and standardise
Formats, categories, dates and units are made consistent using agreed rules.
Validate
The result is reconciled against the source and every decision is documented.
Hand over
You receive the clean data, the log and the script, with a walkthrough.
What I need from you
Inputs to get started
- Raw files or exports (CSV, Excel, database extracts)
- A short description of what each column means
- The business questions the data should answer
- Any known issues or rules, such as valid ranges and naming conventions
- A contact person for questions about the data
What you will get
Your deliverables
- Analysis-ready dataset in the format you prefer
- Data-quality log: issues found, fixes applied and exclusions
- Reproducible Python or SQL script
- Summary of the data before and after cleaning
FAQ
Frequently asked questions
Will my original data be changed?
No. Your originals stay untouched. Cleaning is done on copies and every step is logged.
How do you decide what to remove?
Exclusions follow rules agreed with you and are recorded in the data-quality log, so nothing disappears silently.
Can you combine files from different systems?
Yes. Merging and reconciling sources is part of the service.
Can I rerun the cleaning myself?
Yes. You receive the script that reproduces the result from the raw data.
How long does a cleaning project take?
It depends on the size and condition of the data. After reviewing a sample, I will give you a realistic timeline before work starts.
Get started
Ready to talk about Data Cleaning & Preparation?
Send a short description of your data and what you need to achieve. I'll reply with a scope and a quote. Starting at $40.