Discrete and continuous
Quantitative variables are divided into ‘discrete’ and ‘continuous’. A discrete variable is one that can only take certain values, which are clearly separated from one another – for instance, a sales department can have 2 or 15 or 30 people within it. It cannot, however, contain 38 or 48.1 people. A continuous variable is one that could take any value in an interval. Examples of continuous variables include body mass, height, age, weight or temperature. Where continuous variables are concerned, whatever two values you mention, it is always possible to have more values (in the interval) between them. An example of this is height – a child may be 1.21 metres tall when measured on 27th September this year, and 1.27 metres on 27 September next year. In the intervening 12 months, however, the child will have been not just 1.22 or 1.23 or 1.24 and so on up to 1.27 metres, but will have been all the measurements possible, however small they might be, between 1.21 and 1.27.
Sometimes the distinction between discrete and continuous is less clear. An example of this is a person’s age, which could be discrete (the stated age at a particular time, 42 in 2007) or continuous, because there are many possible values between the age today (42 years, 7 weeks and 3 days) and the age next week (42 years, 8 weeks and 3 days).
5. Write out the definitions from the texts:
Variable (in everyday language);
Variable (in statistics);
Discrete variable;
Continuous variable;
Constant (in everyday language);
Constant (in statistics);
Attributes.
6. Complete the following sentences:
In every day language variable….
In statistical language variable is…..
In every day language constant ….
In statistical language constant is …..
In statistical language, when your variables and constants are categorical…
Quantitative variables are divided into…
A discrete variable is…
A continuous variable is ….
Where continuous variables are concerned….
Sometimes the distinction between discrete and….
7. Ask 10 general questions to the text.
8. Give examples of:
Variable (in everyday language);
Variable (in statistics);
Discrete variable;
Continuous variable;
Constant (in everyday language);
Constant (in statistics).
Present perfect Present Perfect. Present Perfect Continuous
1 Tick (/) the correct underlined verbs, and correct the verbs that are wrong.
I would like to be considered for your degree course In Zoology starting in October next year. I feel I am a good candidate for the course as I (1) have always been interested in natural history and even as a child I (2) have enjoyed studying animals and insects in my garden. Your science faculty has a good reputation and I would very much life to be part of it
As you (3) already saw in Section A of this application, I have a good academic record and I (4) just received the results of my recent exams, all of which (5) have been excellent
In addition, your university attracts me because I enjoy sports and I (6) have read in your prospectus about the large number of sports on offer. Last year I (7) have represented my school at badminton and I (8) played in football teams since I was eleven. I (9) have recently joined a basketball team which competes at a national level.
1 (10) did not travel abroad much yet although as a young child I (11) have been to Singapore and Hong Kong with my family. I realize that I (12) have not spent roach time away from home up to now, but am keen to become more independent
Percentage of UK adults to
have used the Internet
Men women
1 The chart shows the percentage of British adults who have used (use) the Internet since 1995.
2 The number of women who have ever used the Internet _________ (increase) by more than 60% since 1995.
3 The percentage of men who have accessed the Internet ________ (rise) to 60% in 2005.
4 The number of women to have accessed the Internet _________ (rise) each year.
5 The percentage of men who used the Internet _________ (be) greater than the percentage of women from 1995 to 2005.
6 However, British women _________ (overtake) British men in Internet usage since 2005.
7 The total number of people accessing the Internet _________ (grow) each year although the most significant rise _________ (occur) between 1995 and 2000.