We all want the halo effect to work in our favour. According to Wikipedia, halo effect is defined as a
cognitive bias in which our judgments of a person’s character can be influenced by our overall impression of him or her.
Applied to education and essay writing, we can think of it as the teacher evaluating a student based on his initial impression of the student’s ability and performance. With tens and hundreds of scripts to read, teachers can hardly be blamed for judging a book by its cover. After all, it is far more likely that a well written essay follows a good introduction and that a poor essay follows a bad one. This means that it is in a student’s advantage to spend some time to write a good introduction. After all, who wouldn’t want to start a journey with a step in the right direction?
In general,the introduction should achieve the following aims.
1. Define the key words in the question.
It cannot be stressed how important definitions are. Not only do clear definitions demonstrate your understanding of the content to the examiners, more importantly, they allow you to identify the scope of the essay more clearly and ensure that you are sticking closely to the question. Definitions can range from simple one-liner explanations of what national income is or what barriers to entry are, to full paragraphs illustrating how the price mechanism functions or how the short-run profit maximising rule works.
If the question focuses on a specific economy or a certain market structure, it is also a good idea to describe the characteristics of the economy or market structure in focus. This is because you will most likely need to keep using the characteristics in your later arguments and evaluation.
2. State the scope of the question clearly.
Highlight the areas that will be discussed in your essay briefly in the introduction so that the reader can anticipate what is about to come up in your answer. Also, it is better to define the boundaries of the essay clearly from the start, so that you do not go off tangent as you write. It is a common mistake to define the scope either too widely or too narrowly. Using the following question as an example,
The relative importance of the components of the circular flow of income for a small and open economy, such as Singapore, is likely to be different from a large and less open economy, such as the USA.
b. Assess whether a change in the external value of its currency is more likely to have a large impact on Singapore or the USA. 
A scope that is too broad and poorly stated would be:
We will look at how fluctuations in Singapore and USA’s exchange rate impact both economies.
A scope that is too narrow would be:
We will examine how an appreciation in the value of SGD will affect the Singapore economy and compare the effects with the impact of an appreciation of the USD on the US economy.
A proper scope would be something like:
Given the managed-float nature of the SGD, we will examine the effects of deliberate exchange rate policies on the Singapore economy, as well as when there are minor fluctuations within the band. This will be contrasted with the effects of an appreciation and depreciation of the USD, which is under a free floating exchange rate system.
3. Give a tentative stand to the question.
Whenever possible, you should always include your stand in the introduction. However, this is not always possible as most students only manage to formulate their stand in the conclusion, and that is also where most teachers look to when awarding marks for evaluation. Stands and synthesis arguments in economics are usually what stumps most students, as there are almost always at least two opposing points of view for every issue. A good stand should be contextualised, specific and balanced.
This blog will devote an entire post to explain how to formulate a good stand in the near future.
Using the same example as above, a possible stand could be:
Given the small and open nature of the Singapore economy and its huge reliance on exports and imports for growth and sustenance, it is likely that exchange rate changes will have a more significant impact on its economy as compared to the US, which holds the world reserve currency and is largely dependent on its domestic consumption and investment for growth. However, with the US aiming to restructure its economy and boost its export sectors in the medium to long term, the impact of foreign exchange rates on the US economy is likely to increase over time.