A logistics company in Lagos fits a tracking device to every truck. Each device sends position, speed, engine temperature and fuel use every few seconds, all day. A bank records every card swipe, app login and branch visit of every customer. A telecoms firm stores millions of messages, call records and social media posts. Nobody can read this by eye, and an ordinary spreadsheet will not even open it.
Yet buried in it are answers to questions managers have always asked: which routes lose money, which customers are about to leave, which machines are about to fail.
This topic explains what big data is, the five Vs that define it, how it differs from the traditional data that accountants have always used, the principles for managing it well, and the data, information, knowledge and wisdom pyramid that shows how raw data becomes a decision. It builds on the social and ethical issues topic.
The next topic covers the uses, benefits, challenges and risks of big data, data mining and data analytics.
In 30 seconds
Big data means massive, complex data sets that are hard to manage and analyse with traditional methods, and the tools and processes used to gain insight from them. It is defined by five Vs: volume (size, from terabytes to petabytes), velocity (speed of creation and processing), variety (structured, semi-structured and unstructured), veracity (quality and trustworthiness) and value (the insight and outcomes).
Traditional data is structured, smaller, relatively static and easy to hold in ordinary databases and spreadsheets. Big data needs four groups of management principles: quality, accessibility, security and ethics. The data, information, knowledge and wisdom (DIKW) pyramid shows the steps from raw facts to informed decisions. In Nigeria the Nigeria Data Protection Act 2023 governs personal data in any big data project.
Full marks come from defining each term, giving a business example and tying the principles to decision-making.
What big data is, and the five Vs
Big data refers to massive, complex data sets that are difficult to manage and analyse with traditional methods. They include structured, semi-structured and unstructured data, and they often grow very fast. The term also covers the processes, tools and approaches used to gain insight from the data. Big data analytics helps a business deal with problems that traditional analysis could not solve.
- Volume. The sheer quantity of data, from terabytes to petabytes, coming from sensors, social media, text files and business transactions. One petabyte is 1,000,000 gigabytes, which is more than 300,000 high-definition films, and big data means thousands or millions of such units.
- Velocity. The speed and frequency at which data is produced, and so the speed at which it must be processed: batch reports, near real-time or real-time processing, and data streaming. A truck with a tracking device may send about 25 gigabytes an hour, and most of it must be handled at once.
- Variety. The range of forms. Structured data sits in rows and columns in relational databases. Semi-structured data, such as files in standard exchange formats, has some organisation. Unstructured data, such as text, images, video and messaging posts, has none, and most big data is unstructured.
- Veracity. The quality, accuracy and trustworthiness of the data. Data may be repeated, incomplete, inconsistent or noisy, and its origin may be unclear. This is the most contentious V, because poor data weakens the analysis, and in areas such as medical records an inconsistency can do harm.
- Value. The insight and business outcome that analysis delivers. Data that cannot be turned into a better decision has no value, however big it is.
Early descriptions used four Vs (volume, velocity, variety and veracity). Value is the fifth. In an exam, give the five and say which version you are using.
Big data compared with traditional data
Traditional data is structured data that is easy to organise, store and maintain: accounting records, sales information and production results, held in ordinary databases and spreadsheets. Its advantages are easy storage and management, efficient access because of its structure, and low cost for small data sets. Its disadvantages are that it exists only in structured form, handles text, images and video badly, and is hard to scale when inputs grow.
- Volume. Traditional data is small to medium and can be processed by traditional technology. Big data is too large for it.
- Variety. Traditional data is structured in tables. Big data can be structured, semi-structured or unstructured.
- Velocity. Traditional data is relatively static and updated periodically. Big data changes constantly, in real time or near real time.
- Complexity. Traditional data is simple to manage and analyse. Big data needs specialised tools and techniques.
- Value. Big data has greater potential value, because it can show customer behaviour, market trends and other insights that small data sets cannot.
They also have things in common: data quality matters in both, both need analysis (statistics and charts for traditional data, machine learning and other advanced methods for big data), both must be stored, secured and managed, and both can give business value, one from historical patterns and the other from new opportunities.
The data pyramid (DIKW)
The pyramid shows the relationship between data, information, knowledge and wisdom. Each step answers a different question about the original data and adds value.
- Data: raw, unprocessed facts and figures without context. It is the foundation.
- Information: data that is organised, structured and given context, answering who, what, where and when.
- Knowledge: the result of analysing and interpreting information to find patterns, trends and relationships, answering how and why.
- Wisdom: the ability to make well-informed decisions and take effective action based on the knowledge.
Example. A supermarket chain records every till transaction (data). Daily sales by branch and product are totalled (information). Analysis shows that sales of cooking oil in one city rise sharply in the last week of each month, when salaries are paid (knowledge). Management decides to stock more and schedule extra staff for that week, and to agree supplier deliveries in advance (wisdom).
The purposes of the pyramid are to give a framework for the levels of meaning in data; to support data-driven decisions; to give people a common language for communication and collaboration; to be a foundation for analytics, business intelligence and knowledge management; and to help people see how their skills fit into a data-driven organisation.
Principles for managing big data
- Data quality. Accuracy (no errors or inconsistencies), completeness (all necessary data present), consistency (uniform across sources and formats) and timeliness (up to date). Data profiling continuously analyses data for patterns and errors, and data cleansing corrects problems. Poor data gives poor results: garbage in, garbage out.
- Accessibility. Availability to authorised users when needed, ways to find the right data, integration of data from different sources into one view, and controlled sharing for collaboration.
- Security. Protection from unauthorised access, use, disclosure, disruption, modification and destruction; access control by role; encryption of sensitive data; back-up and recovery; compliance with privacy law and industry standards.
- Ethics. Privacy of the people whose data is used; transparency about collection, use and sharing; fairness, so that data is not used to discriminate; accountability, with clear responsibility for data practices; and informed consent.
Other key considerations are data governance (policies and procedures for managing data as an asset), scalability and performance (systems that handle large volumes and complex analysis), and skills and expertise (training and hiring people who can manage and analyse big data).
Where big data is applied
- Business: understanding customer behaviour, optimising supply chains, detecting fraud, managing risk and forecasting.
- Finance: credit risk assessment, fraud detection, algorithmic trading.
- Marketing: targeted advertising, product recommendations, customer segmentation.
- Healthcare: predicting disease, personalised treatment, drug discovery, medical image analysis.
- Transport and public administration: traffic management, public health monitoring, crime prevention, resource management.
Data protection rules for big data in Nigeria
Big data projects often use personal data, so the Nigeria Data Protection Act 2023 applies, with the General Application and Implementation Directive 2025 (in force from 19 September 2025). The main points are these.
- Principles (section 24). Personal data must be processed lawfully, fairly and transparently; collected for specified purposes; limited to what is necessary (data minimisation); accurate; kept no longer than needed; and processed securely with accountability. Collecting everything because storage is cheap breaches data minimisation.
- Lawful basis and consent (sections 25 and 26). Processing needs a lawful basis. Where consent is relied on, the controller must be able to prove it, and silence or inactivity is not consent.
- Impact assessment (section 28). A data protection impact assessment is needed before processing that is likely to be high risk, which includes large-scale processing, new technologies and profiling.
- Automated decisions (section 37). A person has the right not to be subject to a decision based solely on automated processing, including profiling, that has legal or similarly significant effects, subject to stated exceptions.
- Security and breach (sections 39 and 40). Appropriate security measures are required, and a breach likely to put people at risk must be reported to the Commission within 72 hours.
- Cross-border transfers. Sending personal data abroad, for example to a foreign cloud, is allowed only where the receiving country provides adequate protection or safeguards are in place.
These duties are costs and constraints on any big data project and belong in a cost-benefit appraisal. Confirm current Commission notices before advising a real client.
Sources and references
- Nigeria Data Protection Act 2023, sections 24 to 26, 28, 37, 39 and 40, and Part VIII (cross-border transfers).
- Nigeria Data Protection Commission, General Application and Implementation Directive 2025.
These points are stated as at 6 November 2026.
Measuring volume, velocity and data quality
Questions ask you to size the data a business will generate, cost its storage, and measure data quality. The layouts are:
- Daily data. Number of devices × data per device per hour × hours per day.
Use 1 terabyte (TB) = 1,000 gigabytes (GB) and 1 petabyte (PB) = 1,000 TB. - Period volume. Daily data × days in the period.
- Storage cost. Terabytes held × cost per terabyte per month.
- Completeness %. Complete records ÷ total records × 100.
- Duplicate %, invalid %. Duplicate (or invalid) records ÷ total records × 100.
- Timeliness %. Records updated within the required time ÷ total records × 100.
- Cost of poor data. Number of bad records × cost per record per use × number of uses.
Money is in ₦ million to two decimal places unless stated, percentages to one decimal place, and each answer is rounded once, at the end.
Worked examples
Example 1: sizing and storing telematics data. A haulage firm has 120 trucks. Each sends 25 GB of data an hour and runs 10 hours a day. Data is kept for 30 days, and storage costs ₦38,000 per terabyte per month. Required: daily data, 30-day volume, monthly storage cost, and the data in a year.
- Daily data.
120 × 25 × 10 = 30,000 GB = 30 TB. - 30-day volume.
30 TB × 30 = 900 TB. - Monthly storage cost.
900 × ₦38,000 = ₦34,200,000 = ₦34.2m. - Annual data.
30 TB × 365 = 10,950 TB = 10.95 PB. - Comment. The volume and velocity make traditional tools useless. The firm should decide which data has value (engine faults, route times) and discard or summarise the rest, because keeping everything costs money and, where it includes personal data about drivers, breaches the minimisation principle.
Example 2: data quality and its cost. A customer database has 8,000 records. Of these, 7,432 are complete, 264 are duplicates, 160 are invalid, and 7,120 were updated in the last 24 hours. Each record costs ₦450 to mail, and there are 12 mailings a year. Required: the four quality measures, and the yearly cost of mailing duplicates and invalid records.
- Completeness.
7,432 ÷ 8,000 = 92.9%. - Duplicates.
264 ÷ 8,000 = 3.3%.
Invalid. 160 ÷ 8,000 = 2.0%. - Timeliness.
7,120 ÷ 8,000 = 89.0%. - Waste on duplicates.
264 × ₦450 × 12 = ₦1,425,600 = ₦1.43m. - Waste on invalid records.
160 × ₦450 × 12 = ₦864,000 = ₦0.86m. - Total. About ₦2.29m a year, before counting the harm to customer relations. Data profiling and cleansing cost money, but if they cost less than ₦2.29m they pay for themselves.
Expect variants: a different unit (megabytes, petabytes), several device types, storage priced per gigabyte, or quality measures tested against thresholds.
Common mistakes
- Listing the Vs without examples. Give a business example for each.
- Saying big data is just a lot of data. It is also fast, varied and uncertain, and the value comes from analysis.
- Confusing data, information and knowledge. Data is raw; information has context; knowledge explains patterns; wisdom is the decision.
- Forgetting veracity. More data does not mean better data.
- Mixing up units. One terabyte is 1,000 gigabytes and one petabyte is 1,000 terabytes in this working.
- Ignoring privacy law. Personal data in a big data project brings the Nigeria Data Protection Act 2023 into the answer.
Quick revision
- Big data: massive, complex data sets and the tools to gain insight. Five Vs: volume, velocity, variety, veracity, value.
- Traditional data: structured, smaller, relatively static, simple, cheap to hold.
- Principles: quality (accuracy, completeness, consistency, timeliness, profiling, cleansing), accessibility, security, ethics (privacy, transparency, fairness, accountability, consent).
- DIKW: data (raw), information (context), knowledge (patterns), wisdom (judgement and action).
- Nigeria Data Protection Act 2023: section 24 principles, section 28 impact assessment, section 37 automated decisions, section 40 breach notice within 72 hours.
How the marks are earned
- State: one mark per item, with an example.
- Distinguish: a point for each side of each difference.
- Explain the pyramid: each level defined, with the question it answers and a business example.
- Calculate: show units and workings; give the conclusion.
Practice questions
These are original questions, written in the style of the Skills examination. Work each one before you open the answer.
Recall check: multiple choice
Question 1. The speed at which data is created and must be processed is its:
- Volume
- Variety
- Veracity
- Velocity
Show the answer
D. It may be batch, near real-time or streaming.
Question 2. Most big data is:
- Perfectly structured
- Unstructured
- Always accurate
- Small
Show the answer
B. Text, images, video and messages have no fixed structure.
Question 3. Veracity refers to the:
- Quality and trustworthiness of the data
- Size of the data
- Speed of the data
- Cost of the data
Show the answer
A. Data may be incomplete, inconsistent or noisy.
Question 4. Which is a feature of traditional data rather than big data?
- Real-time streaming
- Mostly unstructured
- Structured and relatively static
- Needs specialised tools to process
Show the answer
C. It sits in tables and is updated periodically.
Question 5. In the data pyramid, data that is organised and given context is:
- Wisdom
- Information
- Knowledge
- Raw data
Show the answer
B. It answers who, what, where and when.
Question 6. The level of the pyramid that explains how and why is:
- Knowledge
- Data
- Information
- Wisdom
Show the answer
A. Knowledge comes from analysing information for patterns and relationships.
Question 7. Data profiling means:
- Deleting all old data
- Printing reports
- Continuously analysing data to find patterns, errors and inconsistencies
- Encrypting data
Show the answer
C. Cleansing then corrects the problems found.
Question 8. Collecting far more personal data than a project needs conflicts with the principle of:
- Timeliness
- Accessibility
- Scalability
- Data minimisation
Show the answer
D. It is one of the principles in section 24 of the Nigeria Data Protection Act 2023.
Question 9. Under the Nigeria Data Protection Act 2023, a breach likely to put people at risk must be reported to the Commission within:
- 7 days
- 30 days
- 72 hours
- One year
Show the answer
C. Section 40 sets 72 hours from becoming aware of the breach.
Question 10. One petabyte, in this topic’s units, equals:
- 1,000 terabytes
- 1,000 gigabytes
- 100 terabytes
- 10,000 gigabytes
Show the answer
A. One petabyte is 1,000 terabytes, or 1,000,000 gigabytes.
Section B style: written questions
Question 11 (10 marks). (a) State the five Vs of big data, with a business example of each. (5 marks) (b) Distinguish big data from traditional data under FIVE headings. (5 marks)
Question 12 (15 marks). A logistics firm has 80 vehicles. Each sends 25 GB of data an hour and operates 12 hours a day. Data is held for 30 days, and storage costs ₦40,000 per terabyte per month. Use 1 TB = 1,000 GB and 1 PB = 1,000 TB.
(a) Calculate the daily data in terabytes. (3 marks) (b) Calculate the volume held after 30 days. (3 marks) (c) Calculate the monthly storage cost. (3 marks) (d) Calculate the data produced in a year, in petabytes. (3 marks) (e) Comment on the implications of velocity and volume for the firm. (3 marks)
Question 13 (20 marks). A bank’s customer database has 12,500 records. Of these, 11,625 are complete, 375 are duplicates, 250 are invalid and 10,625 were updated in the required time. Targets: completeness at least 95%, duplicates not above 2%, invalid records not above 1%, timeliness at least 90%. Each record costs ₦520 to mail and there are 12 mailings a year.
(a) Calculate the four measures and compare each with its target. (8 marks) (b) Calculate the yearly cost of mailing duplicate and invalid records. (4 marks) (c) Explain the data, information, knowledge and wisdom pyramid, using an example from the bank. (8 marks)
Model answers
Show the model answer to Question 11
(a) Volume:
- the quantity of data, for example millions of card transactions
- velocity: the speed of creation, for example sensor data from vehicles
- variety: structured, semi-structured and unstructured forms, for example text, images and tables
- veracity: quality and trustworthiness, for example duplicate or inconsistent customer records
- value: the insight obtained, for example finding which customers will leave (1 each)
(b) Volume:
- small to medium against very large
- variety: structured against structured, semi-structured and unstructured
- velocity: static and periodic against real-time or near real-time
- complexity: simple against needing specialised tools
- value: limited against high potential (1 each)
Show the model answer to Question 12
(a) 80 × 25 × 12 = 24,000 GB = 24 TB (3).
(b) 24 × 30 = 720 TB (3).
(c) 720 × ₦40,000 = ₦28,800,000 = ₦28.8m (3).
(d) 24 × 365 = 8,760 TB = 8.76 PB (3).
(e) The data arrives continuously and in large amounts, so it needs real-time or near real-time processing tools rather than a spreadsheet; storage cost is large, so the firm should decide which data has value and discard or summarise the rest; and personal data about drivers is subject to data protection law (3).
Show the model answer to Question 13
(a)
- Completeness 11,625 ÷ 12,500 = 93.0%, below 95%, not met (2).
- Duplicates 375 ÷ 12,500 = 3.0%, above 2%, not met (2).
- Invalid 250 ÷ 12,500 = 2.0%, above 1%, not met (2).
- Timeliness 10,625 ÷ 12,500 = 85.0%, below 90%, not met (2).
(b) Duplicates 375 × ₦520 × 12 = ₦2,340,000 = ₦2.34m; invalid 250 × ₦520 × 12 = ₦1,560,000 = ₦1.56m; total ₦3.9m a year (4).
(c) Data is raw facts without context: each account balance and transaction (2). Information is data organised and given context: monthly spending by customer segment (2). Knowledge comes from analysing information for patterns, explaining how and why: customers who stop using the app for 60 days and then reduce deposits tend to close their accounts (2).
Wisdom is the judgement and action based on it: contact those customers with a retention offer and redesign the app experience (2).
Spotted a mistake? Tell us and we will check it.