Write an essay defines Type I and Type II errors, as they relate to environmental studies, and discusses the differing importance and implications of these two kinds of errors.


Assignment 1: more information

Assignment 1: More about the task

Task From the Unit Information: “The design of environmental studies is without exception a compromise between cost and information. This translates almost directly into a balance between Type I and Type II errors. Define Type I and Type II errors, as the relate to environmental studies, and discuss the differing importance and implications of these two kinds of problems. Use examples of different kinds of monitoring situations (i.e. objectives) in your essay.

Assessment criteria Definition: 20% of mark

Assessed on the basis of: · the clarity of the definition, · the completeness of the definition, and · the accuracy of the definition.

Discussion of Type I & II errors: 40% for each type

Assessed on the basis of: · the range of examples used, · the validity of the examples used, · the way in which the examples are used to display how the effects of the errors vary in different

circumstances, and · the way in which the examples are used to display how the significance of the errors varies in dif-

ferent circumstances.

More about the first part of the essay: the definition The Study Guide, tapes and readings actually discuss the nature of Type I and II errors in some depth. In this part of the essay I am asking you to translate this discussion into your own words and, by doing this, convince me that you really understand the nature of these errors and how they arise. The three assessment criteria for this part of the essay focus on what I think is crucial here.

· The clarity of your definition. Can I easily understand what you have written and what you mean? You usually need to understand something fairly well to be able to explain it clearly.

· The completeness of your definition. Does your definition, and discussion, cover all the important issues? It is important here not to go “overboard”. For instance (and I’ll give you this tip for free), one issue that is relevant to Type II errors is power. But, while it is appropriate to consider power, an extended discussion of what affects power is not.

· The accuracy of your definition. Simply, is what you have written correct? It would, for instance, not be correct to state that the chance of a Type I error was influenced by the cost of the instruments used to collect the data!

I’ve said this before but it is important enough to be worth repeating: this section of the essay is worth only 20% so 20 marks is the most you can get, regardless of how good your definition is. Submitting a five page essay, with four pages devoted to the definition, is not likely to be a successful strategy!

More about the second part of the essay: the examples This is the main part of the essay. In the past, I’ve been hesitant to provide examples because I didn’t want to steer people’s thinking in particular directions. This year I’ve decided to include an example (although a very silly one) to give you a bit more guidance.

Assignment 1: more information

First, however, I’m going to discuss a bit more what I mean by the words “importance”, “implications”, “effects” and “significance”. I’ll also use these when discussing my example to put their meaning in context.

· Implications and effects: By these words I mean, what are the possible or potential consequences of the error (Type I or II)? More simply, what might happen?

· Importance and significance: By these words I mean, how important or significant are these poten- tial consequences? More simply, would they create major problems or only minor problems?

I deliberately used the key words (importance, implication, effect and significance) in my example but primarily for illustrative purposes. You do not need to use these particular words, although you do, obviously, have to discuss these issues.

The example

The search is on for alternative sources of energy because, as everyone knows, burning fossil fuels is Destroying The World. Professor Sprong believes that he has found the answer. He plans to siphon off the hot air generated during political debates in the various Federal, State and Territory parliaments and use it to drive turbines to generate electricity. The attractions are obvious: the resource is (alas) abundant and (sadly) renewable. And it is a waste product of the political process which, up until now, has been of no use or value commercially.

Unfortunately, just as the project is about to get the “go ahead” – after being fast-tracked through a rigorous twenty minute environmental approval process – there is a snag: the RSPCP (Royal Society for the Prevention of Cruelty to Politicians) gets a court injunction on the grounds that the effects on the health of politicians have not been adequately assessed. (Rumours that the judge muttered “Who cares?”, before approving the application for an injunction on procedural grounds, have not been substantiated.)

One issued raised by the RSPCP was that the heat generated by political debate is an important source of warmth for members during the colder months, particularly in the southern capitals. A pilot study is established to trial the process and assess its effects. It is designed to test the following null hypothesis:

· H0: Siphoning hot air from the chamber will not adversely affect the health of members.

The alternate hypothesis is: · HA: Siphoning hot air from the chamber will adversely affect the health of members.

A Type I error in this study would result in the null being rejected, leading to the conclusion that the process did have effects, when, in fact, it did not. In contrast, a Type II error would result in the null being accepted, leading to the conclusion that the process (unfortunately) did not have effects, when, in fact, it did.

Type I error: The most likely consequence of this result would be that the project would be halted. The effect of this would be to increase, or at least not reduce, reliance on other, potentially more expensive and less environmentally friendly, sources of alternative energy. This would increase costs to the consumer, potentially forcing poorer individuals to cut back on their energy use. This would lower their standard of living and potentially endanger their health (for instance, if they chose to keep up with their favourite soap at the expense of looking after their health). There could also be flow on effects on the environment. The alternative to this alternative source of alternative energy would be to retain, or increase, reliance on fossils fuels. The implications of this are so obviously Bad that no further comment is necessary.

Clearly, these problems would be of some significance. It is critically important that Western Society reduces its reliance on fossil fuels and anything that interferes with this is also a Bad Thing. If alternative, but more expensive, sources of energy were pursued, the burden of the increased costs would be most severe on the poorer and more disadvantaged members of society. Their quality of life would suffer, while the Rich Fat Cats could watch Neighbours all day long. This would further fragment society and lead to massive civil unrest.

Type II error: In contrast, a Type II error would probably result in a false sense of security and the project would probably go ahead. The immediate effect of this would be the availability of cheap source of alternative energy. More expensive sources would not be required (or required so much), benefiting the consumer, and reliance on fossil fuels would decrease, benefiting the environment. A longer term implication is that the health of the politicians would suffer. The weaker politicians, and those in Tasmania

Assignment 1: more information

and Victoria, would be the first to go. Labouring under the false sense of security flowing from the pilot study, investigators would pursue numerous blind alleys so it could (hopefully) be quite some time before the real cause of the problem was identified. It is possible that government in the southern states could be damaged to the point of collapse; in which case, the Northern Territory (being least susceptible to the lack of heat) would probably take over the rest of Australia. Whether this would be a Good or Bad Thing for society or the environment is difficult to judge. Eventually, of course, the real cause would be identified and, assuming that the scientists revealed the results of their studies (this would require careful consideration of multiple and difficult public interest issues), we would be back to square one.

These problems would also be important and significant. It is, however, more difficult in this situation to evaluate the seriousness of the different possible outcomes. Certain eventualities might actually have benefits for society, the environment or both. For instance, the collapse of government might hinder development – a Good Thing – or it might eliminate controls – a Bad Thing.

Given the uncertainty surrounding the significance of the effects of a Type II error, it is difficult in this situation to decide which of the two kinds of errors would be worse for society or the environment.

How to display your examples and set out your essay

The format I used above is fine. Some students have used a tabular format. Whatever you do, remember that this is an essay so most of the discussion has to be in sentences and paragraphs. It is a good idea to use headings and subheadings to organise your essay (I have heard that some staff believe that essays do not incorporate headings but I do not subscribe to that point of view!).

On different kinds of examples, circumstances and objectives

The topic makes specific mention of different kinds of situations and different circumstances: both refer to the same thing, although my use of the word “monitoring” probably confuses things a little. I encourage you to interpret the term “environmental study” broadly but also to think directly in terms of hypotheses about environmental issues which might be tested. I’m not going to be too specific here because I want you to come up with the examples but environmental issues are things such as pollution, invasive species, habitat destruction, habitat reconstruction or rehabilitation, rare or threatened species, harvesting, farming…and I’m sure you can add more.

The examples you use can be related to a single situation or deal with separate situations. One student came up with a range of related (fictional) examples affecting a single river system but most students seem to find it easier to use unrelated examples.

It is important that your examples cover a range of different types of situations or issues: this one of the specific assessment criteria. For instance, it is not likely to be revealing to use as a set of examples, lead pollution in the Swan River, cadmium pollution in the Swan River, mercury pollution in the Swan River and zinc pollution in the Swan River.

Sources of examples

You can take your examples from reports in the media, scientific papers, web sites, government reports or you can just make them up. If I was doing this assignment, I would do the latter. You may find it easier to base your examples on real situations. It is entirely up to you. If, however, you do refer to a specific situation, drawn from an existing source (for instance, a published paper or an environmental impact statement), then you should cite that source in your reference list as usual.

What the examples do NOT have to be

The examples do not have to be real (although they should be realistic enough for your discussion to make sense), as should be apparent from the previous section, or confirmed. By “confirmed” I mean that you do not need to know whether a Type I or II error actually occurred. The aim is to consider the consequences of different outcomes in different situations.

Assignment 1: more information

More on the assessment criteria for the examples

The interpretation of three of the assessment criteria for this part of the essay (range of examples used; way in which the examples are used to display how the effects of the errors vary in different circumstances; way in which the examples are used to display how the significance of the errors varies in different circumstances) should now be clear.

The one remaining is this: the validity of the examples used. This simply refers to whether or not the conclusions you have drawn make sense in the context of the particular example being discussed. For instance, I would probably not be impressed if you suggested that an accidentally released GMO (genetically modified organism), which was killed by sunlight or saltwater, nonetheless threatened to destroy the entire Great Barrier Reef. I would be less impressed if you concluded that such an event would be of minor significance!

Final remarks That covers the main questions that students usually have about this assignment. If you have others, please contact me (phone, email, chat or in-person).