Let us take a break from comparison questions today because we have done quite a bit over the past week.
One issue that troubles many candidates who take classes is that often the teacher doesn’t cover all the different types of maths question: bar charts, line graphs, tables and pie charts. In our classes we do manage to cover all these types and additional issues with maths questions but the truth is, most of the time, candidates don’t have to worry. None of these different types create any special sort of problem: no matter how the data is presented, you are basically looking for two things - TRENDS and MAGNITUDE differences. As we have seen, sometimes only the trends matter, sometimes only the magnitudes matter and OFTEN BOTH matter.
But the way the data is presented usually makes no difference. Let us look at an example of this.
BAR CHART
The bar chart here presents information comparing the percentage of household spending in a number of different areas.
TABLE
But look at this data:
ITEM .......................1955 ...1985 ...2015
housing ......................33 .......18 ......14
electricity & water .......18 .......21 ......28
Food ...........................15 .......18 ......10
education ....................20 .......24 ......30
holidays ........................8 .......11 ........8
entertainment ...............6 ........8 .......10
As we will see in a minute, the same information is contained here.
PIE CHART
and finally look at this data presented in pie charts.
These pie charts again contain exactly the same information as the table and the bar chart.
NOTE:
Although we could draw a line graph for this data, it would not really be very sensible because we only have annual figures for three years. If we had annual data for many years, then it would be more meaningful to use a line graph with a continuous line from year to year. Nevertheless, you will understand the point being made here that the type of data presented makes no basic difference to the way you must answer the question.
THE BIG PICTURE
This same analysis can be made from any one of the data sources presented here. Although quite a lot of data is presented, in principle, it is not difficult.
1. TRENDS
Years are presented on the data so we can look for trends:
INCREASE IN PERCENTAGE OF SPENDING
electricity & water
education
entertainment
DECREASE IN PERCENTAGE OF SPENDING
housing
food
FAIRLY STABLE (in fact, it actually PEAKED)
holidays
PEAKED: DETAIL OR NOT
Note this last category is not really just stable, there is more to the story than this. In this case, the percentage of spending rose to a peak and then fell back. Is this important? Well, in general, it depends on the data in the question. Here an increase of around 35%, in relative terms, is followed by a decrease of around 27%, in relative terms, so these changes are not huge but they are not insignificant. This is a judgement that needs to be made from question to question when you see peaks, and also dips, in Task 1 Writing questions.
2. MAGNITUDES
The magnitudes can easily be mentioned in the question as part of the description of trends, perhaps with the exception of the proportion of spending on holidays and entertainment, which saw the lowest proportion of spending, and we can deal with that very simply in a single RELATIVE CLAUSE as done in this sentence.
IN BRIEF
One approach to writing the overview might be:
“Overall, the proportion of spending increased significantly on electricity & water, education and entertainment over the period while it saw a decrease for housing and food. In addition, the percentage of expenditure on holidays was relatively stable, in comparison to most other items.”
Note that it would be possible to replace this last sentence with:
“In addition, the percentage of expenditure on holidays rose to a peak and then fell back.”
- this is entirely accurate and it really doesn’t take any longer to write IF you realise that this somewhat erratic behaviour has occurred.
IN SHORT
The way the data is presented really makes no difference to the way candidates must approach the question. The big picture statement above is the same no matter how the data is presented and the ‘Details” section, which would come after this would also be the same.
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