скачать книгу бесплатно
Every day in our lives, we hear and read about many different types of information in the form of data. Data can tell us interesting and important details about the world around us but it can be challenging to understand the facts and figures.
Statistics is a mathematical science that helps us to make sense of data that has been counted, measured, asked about or observed. It involves four main activities:
Glossary
method A method is a particular way of doing something.
technique A technique is a particular method of doing an activity, usually a method that involves practical skills.
Collecting data – first of all, we decide what type of data we are interested in, which method we shall use to collect the data, and where we would like to collect it from.
Organizing data – we use a range of different techniques to summarize the data we have collected so that we can see interesting features or patterns in the information.
Interpreting data – we use the results of calculations to help us make comparisons about different sets of data, to answer questions and make decisions about the world around us.
Glossary
feature A feature of something is an interesting or important part or characteristic of it.
Presenting data – when we have found out interesting facts about our data, then we will need to display and present the information to other people so that they can understand our conclusions.
Exercise 5
Choose a newspaper or news-related website and look for reports that use statistics to help explain the main points of the article. Think about these questions:
How was the data collected?
What type of organization is using the statistics?
What interesting features or patterns were found in the data?
How is the data presented?
Statistics is important in many different subject areas. The following diagram lists some examples of the type of data that might be collected and used:
Some terminology
In statistics, we use two key words: variable and observation. It is important to understand the difference in their meanings. A variable is a characteristic or an attribute that can have different values; an observation is the value of a variable that has actually been counted, measured or observed. Some variables are shown below, with a list of possible observations next to each one.
Glossary
variable A variable is a factor that can change in quality, quantity, or size, which you have to take into account in a situation.
characteristic The characteristics of a person or thing are the qualities or features that belong to them and make them recognizable.
attribute An attribute is a quality or feature that someone or something has.
The observations for a variable can be described as quantitative or qualitative, depending on what the information is about. Quantitative data is something which can be measured or counted using a number. Qualitative data represents a characteristic that uses words to describe it but does not use any numbers.
Examples of quantitative variables are:
time taken to complete a test
the number of books in a library
the highest temperature in a month
Examples of qualitative variables are:
the nationality of people in a cinema
the favourite sport of children in a school
the colours of balloons at a party
Exercise 6
Match the words on the left to their definitions on the right.
Exercise 7
State whether each of the following variables is quantitative or qualitative:
1 number of pages in a book
2 names of students in a class
3 hair colour
4 weight of apples in a bag
5 height of trees in a park
Exercise 8
Answer these questions.
1 Explain the difference between a quantitative and a qualitative variable.
2 Give an example of each type of variable.
3 Explain why:
‘type of tree’ is a qualitative variable
‘number of pupils in a class’ is a quantitative variable
Exercise 9
Without looking back at the section ‘What is statistics?’, put these statistical stages into the correct order.
1 organize data
2 present data
3 collect data
4 interpret data
Exercise 10
Use the words in the box to complete these questions about the stages above.
data features patterns sets of data
display method present technique
1 What type of ________are we interested in?
2 Which data collection ________shall we use?
3 What ________shall I use to summarize my data?
4 What interesting ________or ________can I see?
5 What questions do my ________answer?
6 What is the clearest way to ________and ________my data?
Exercise 11
Match the questions in Exercise 10 to the stages in Exercise 9.
Using spreadsheets
You can store, organize and present your data in a computer program called a spreadsheet.
Glossary
grid A grid is something which is in a pattern of straight lines that cross over each other, forming squares. On maps the grid is used to help you find a particular thing or place.
row A row of things or people is a number of them arranged in a straight line.
intersection An intersection is a place where lines or roads meet or cross.
cell A cell is one of the small squares in a chart or spreadsheet into which you can add a single piece of data.
A spreadsheet appears as a table or grid containing a set of rows and columns. Rows are displayed horizontally on the grid and each one is labelled with a number (1, 2, 3 …); the label for each column is a letter (A, B, C …) and columns are displayed vertically across the grid.
The empty spreadsheet grid shown below has eight rows and five columns, but a spreadsheet in a computer program will have many, many more rows and columns.
The intersection of a row and a column is called a cell. Each cell has its own name, which consists of the letter of the column followed by the number of the row. The highlighted cell in the spreadsheet grid shown above is called C5 – it is where column C and row 5 meet.
Tip
Use the glossaries to help you with some of the key words in this book. Consider making similar lists for your modules to help you learn key words.
Exercise 12
Look at the section of a spreadsheet below, and answer the questions.
1 What is contained in the following cells?
a A6
b B3
2 What is the reference for the cells that contain the following?
a The number ‘53%’
b The word ‘Statistics’
The data values in each spreadsheet cell can be displayed in different ways depending on how the information is described. You can use:
text
numbers
currency
dates and times
The spreadsheet opposite records the food purchased by a shopper at a supermarket. Row 1 in this grid is used to show the names of the columns so that it is easy to understand what information is being stored.
A spreadsheet is very useful for performing simple calculations. It uses formulae to perform operations such as addition, subtraction and multiplication.
The following spreadsheet shows the different nationalities of students enrolled on an English course. It includes a formula which uses the individual numbers of each nationality to calculate the total number of students enrolled on the course. The formula is usually hidden from view and only the result is displayed.
Glossary
formula A formula is a group of letters, numbers or other symbols which represents a scientific or mathematical rule.
The formula SUM(B2:B8) is used to calculate the total of number of students enrolled on the course. It adds up the numbers in cells B2 to B8. If a number in one of these cells is changed, then the result of the formula is automatically updated by the spreadsheet.
So, if another French student enrols on the course, then the cell B5 becomes 4 and the total in cell B10 is changed automatically to 44 to include the new student.
Once you have organized your data in a spreadsheet, it is then possible to use the computer program to create graphs and charts to display the information in a visual way. The bar chart below has been created using the data in the previous example.
