[寫作] The correct use of "trend"

在雅思的作文考試中，題目常要求考生觀察圖表並用自己的語言傳達圖表呈現的信息，但是有些圖表只是數據紀錄、有些是對照與比較、有些是趨勢走向，因此，我們建議考生在使用"trend"這個字時，應該特別小心。

Many students try to use the term "trend" in their writing, however...
they often use it erroneously. A "trend" requires at least 3 points of reference and ideally more. And it is used correctly to describe overall characteristics of data over time. A correct use of "trend" would be in regard to stock prices, say for example HTC stock goes down in price for six weeks, so "over a six week period, HTC's stock experienced a downward trend." We can use the term "trend" here because we have 30 sets of data that should be consistent, mostly always finishing down.  

If you scroll down, or look below, you can see two examples - one negative and one positive - to illustrate when NOT to use and when it is correct to use "trend." 

Because we only are given the data for two years in these pie charts, the most we can say is that some categories of spending increased, decreased, or remained the same.  One cannot infer a trend based on this data.

Source(s): http://www.usfederalbudget.us

In the second example (part a), you can see very clearly Australia's population growth in the data given starting from 1911 and continuing until 2011. There has never a better example of a case when using "trend" is ideal. All the conditions of when to use "trend" are present. First, it is completely consistent. Population growth continued through out the century, sometimes a little faster and sometimes a little slower, but always upward. This is a "trend." The second condition is that we have data for a hundred years so we have a period of time in which to see that an actual trend took place.  Moreover, we have 11 sets of data that are graphed on the chart of part a. So, clearly, this is a "trend." Hence, "Over the period of a century starting from 1911 we can clearly see the ever upward trend in Austria's population growth."

Australia's population (a)

However, as we can see more clearly in the second chart in part b, the real story is a  little bit more complicated. Part a's chart graphed data for the census taken every ten years. It seems there was some attempt to show a little bit more definition because you can see a small dip around the time of WWI. Yet, as we can now see in part b annual figures, while with the exception of 1916 or 1917, that although growth continued it wasn't really as consistent as the previous chart allows it to seem. What actually happened was that beginning after WWII around the late 40's or early 50's, the annual data suggests there were spikes in growth every few years. So we can still say that overall the general trend was one of growth, yet, it is not as easy to term this data a trend because it's somewhat inconsistent. Hence, the best one can say in regard to using "trend" is: "Australia with the exception of the period of WWI did experience growth; however, the rate of growth annually fluctuated somewhat. Nonetheless, there did seem to exist a generally upward trend in more significant population growth beginning around 1948."

Annual population growth (b)

Source(s): http://www.abs.gov.au; Australian Historical Population Statistics, 2008 (cat. no. 3105.0.65.001) and Australian Demographic Statistics, December 2011 (cat. no. 3101.0).