One match, millions of numbers
A football match has 22 players. Each player wears a small tracker (a device that sends its place). The tracker says where the player is, 10 times every second.
That is 220 numbers every second. After 90 minutes, it is more than a million. Add the ball, the cameras and the fans' phones. How do you keep and use all of it?
Key words
| Word | What it means | Example |
|---|---|---|
| Big Data | Data that is so large, fast or mixed that normal tools cannot work with it. | All the tracker data from a league |
| Dimension | One way to measure or describe something. Big Data has six. | Volume is one dimension. |
| Volume | How much data there is. | 1,000,000 readings |
| Variety | How many different kinds of data there are. | Numbers, video and text |
| Variability | How much the data changes in shape, size or meaning. | A small match and a big final |
| Velocity | How fast the data arrives. | 10 readings every second |
| Veracity | How true and correct the data is. | A broken tracker gives false data. |
| Value | How useful the data is to the people who want it. | It helps a coach choose a team. |
| Sensor | A device that measures something and sends a reading. | A tracker, a thermometer |
The cells students fill in are left blank in this preview.
What is Big Data?
Big Data is data that is too big, too fast or too mixed for normal tools. A spreadsheet on your laptop cannot hold it.
There is no single number where data becomes "big". Big Data has six dimensions. A dimension is one way to measure it. All six start with the letter V.
Quick check: is it Big Data?
Have a go
Quick check: is it Big Data?
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
The first two Vs
Volume is how much data there is. A match gives millions of readings.
Variety is how many kinds of data there are. The match gives numbers from trackers, video from cameras, and words from fans on social media. Each kind needs a different way to store it.
Worked example: how many readings?
| Step | Sum | Answer |
|---|---|---|
| One tracker, one second | 10 readings | 10 |
| 22 trackers, one second | 22 times 10 (22 x 10) | 220 |
| 22 trackers, one minute | 220 times 60 seconds | 13,200 |
| 22 trackers, 90 minutes | 13,200 times 90 | 1,188,000 |
The cells students fill in are left blank in this preview.
Try it: count the readings
players = 22
per_second = 10
seconds = 60 * 90
total = players * per_second * seconds
print("Readings in one match:", total)
# Change per_second to 25 and press Run again.
# Each reading is 2 kilobytes (a small amount of storage). Print total * 2 too.
Velocity and variability
Velocity is how fast the data arrives. 220 readings a second must be saved as they come. If the system is too slow, it loses some readings.
Variability is how much the data changes. A small match on a Tuesday and a big final give very different amounts of data. The meaning can change too. In slang, "sick" can mean very good.
Veracity and value
Veracity is how true and correct the data is. A broken tracker says a player ran 90 metres in one second. That is false data, so you cannot trust it.
Value is how useful the data is. Data costs money to keep. If nobody uses it, it has no value, and you should not keep it.