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Presentation and Representation

1. What are the advantages and disadvantages of graphic displays in presenting data?

2. What is the principal difference between validity and reliability?

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1. What are some explanations for the over representation in arrests and incarceration of people from ethnic or racial minority groups? Do you agree or disagree with these explanations?

2. Explain some of the known causes of wrongful convictions. What are some possible remedies?

3. Explain some of the known causes of wrongful convictions. What are some possible remedies?

Solution Preview

What are the advantages and disadvantages of graphic displays in presenting data?

The advantages are that the summary of a paper, especially a quantitative one, can be clearly summarized in a box or chart. These can communicate more effectively than prose, which sometimes sounds awkward when it is merely reciting number after number. Graphics seem to make more sense in quantitative data regardless.

In order for these advantages to be realized, several things have to occur. Entities must be properly labeled. The units of measurement should also be clear (billions, inches, gallons, votes, etc). The source should always be specified. A legend should also be included so variables become clear. Abbreviations, if used, should bear some relation to the word they are abbreviating.

These give us hints at the disadvantages of graphics. They can be used to manipulate. Bring colors might give the the impression that a piece of a pie or a bar is more significant than it is. Using scale is another way to manipulate the reader. For example, if one is using a chart with points over time (such as measuring unemployment rates from 1960-1980), it is very easy to show severe upturns and downturns even when the scale is very small. Depending on how you scale the variable you're measuring, a huge dip can only represent .5% change. These can also manipulate the reader (Klass, 2002).

What is the principal difference between validity and reliability?

Reliability concerns the ability of a specific method to return regular results. That is to say, that the method one is using is consistent and accurately reflects the data and differences among them. Different kinds of reliability are replication. Using the same data and tools under the same conditions, a reliable approach will lead to the same result.

Another version of reliability is using a different method to test the same set of data. The method must be vaguely similar to the present one (they must be quantitative, for example), but, so long as they are otherwise compatible, different methods should lead to the identical result.

Another concerns time. If we are measuring change over time, say, unemployment between 1960-1980 and are coming up with "universal" conclusions from that, we might also want to control for periods within that 20 years. There could be great jumps and gaps that need to be accounted for. Sometimes, a long period of time might "smooth" out differences, while a shorter length of time puts differences and changes in sharp relief.

The point of reliability is that quantity ...

Solution Summary

The advantage and disadvantages of graphic displays in presenting data is determined. The known causes of wrongful convictions are examined.

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