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Study Questions, Gipe 5 and Harvey and Goudvis, 15
1. What is the difference between assessment and evaluation?
2. Define these terms that are important for assessment.
Norm-Referenced
Test
Validity
General:
Content:
Construct:
Reliability
Standard Error of
Measurement
CriterionReferenced Test
Target level of
Mastery
3. Label the following illustrations with the kind of score they represent.
Illustration
Label
4. Go to http://www.teachersandfamilies.com/open/parent/scores2.cfm and read all
pages of the assessment primer for parents there. List three things you learned about
formal testing that you didn’t know before reading the page.
5. Go to http://tusdstats.tusd.k12.az.us/planning/resources/dr_gregg/dr.html#nce and
read all pages of this assessment resource for teachers. List three things you learned
about formal testing that you didn’t know before reading this page. How is it
different from the parent page you visited in #4?
6. Visit the website for the Gates-McGintie test and read its explanations of scores.
What additional scores to you see on this site that are not mentioned in your book?
How do these explanations compare with what you read?
http://www.riversidepublishing.com/products/gmrt/support.html#9
7. What does formal testing tell teachers about their students? Why is knowing this
information important?
8. What are Reading Survey Tests? Search the web for information on the four tests
listed in Gipe and select the one you would most recommend your principal buy for
your school. Explain your reasoning.
9. What are Standardized Diagnostic Reading Tests? Which one is most commonly
used by classroom teachers? Search the web for information about this test and tell
why you think teachers use it.
10. How do Harvey and Goudvis recommended teachers teach the test-taking genre of
writing to children? Do you agree with them that it is a separate genre or writing?
Why?
11. What are the steps Harvey and Goudvis recommended students use when they take a
test?
12. Read though the supplemental information included and highlight what the key
points are.
Standard scores indicate where your score lies in comparison to a norm group. For
example, if the average or mean score for the norm group is 25, then your own score can
be compared to this to see if you are above or below this average.
Percentile Scores
A percentile score is another type of converted score. Your raw score is converted to a
number indicating the percentage of the norm group who scored below you. For example,
a score at the 60th percentile means that the individual's score is the same as or higher
than the scores of 60% of those who took the test. The 50th percentile is known as the
median and represents the middle score of the distribution.
Percentiles have the disadvantage that they are not equal units of measurement. For
instance, a difference of 5 percentile points between two individual’s scores will have a
different meaning depending on its position on the percentile scale, as the scale tends to
exaggerate differences near the mean and collapse differences at the extremes.
Percentiles can not be averaged nor treated in any other way mathematically. However,
they do have the advantage of being easily understood and can be very useful when
giving feedback to candidates or reporting results to managers.
If you know your percentile score then you know how it compares with others in the
norm group. For example, if you scored at the 70th percentile, then this means that you
scored the same or better than 70% of the individuals in the norm group.
This is the score most often used by organizations when comparing your score with that
of other candidates because they are so easily understood they are very widely used when
reporting results to managers.
The characteristic way that test scores tend to bunch up around the average and the use of
percentiles in the interpretation of test results, has important implications for you as a job
candidate. This is because most aptitude tests have relatively few questions and most of
the scores are clustered around the mean. The effect of this is that a very small
improvement in your actual score will make a very substantial difference to your
percentile score.
To illustrate this point, consider a typical aptitude test consisting of 50 questions. Most of
the candidates, who are a fairly similar group in terms of their educational background
and achievements, will score around 40. Some will score a few less and some a few
more. It is very unlikely that any of them will score less than 35 or more than 45.
Looking at these results in terms of percentiles is a very poor way of analyzing them and
no experienced statistician would ever use percentiles on this type of data. However, nine
times out of ten this is exactly what happens to these test results and a difference of three
or four extra marks can take you from the 30th to the 70th percentile. This is why
preparing for these tests is so worthwhile as even small improvements in your results can
make you appear a far superior candidate.
Different Norming Systems
There are several different norming systems available for use, which have strengths and
weaknesses in different situations. These can be grouped into two main categories; rank
order and ordinal.
Z-scores
To overcome the problems of interpretation implicit with percentiles and other rank order
systems various types of standard scores have been developed. One of these is the Zscore which is based on the mean and standard deviation. It indicates how many standard
deviations above or below the mean your score is.
The Z-score is calculated by the formula: Z=X-M/SD Where:
Z
X
M
SD
=
=
=
=
standard score
individual raw score
mean score
standard deviation
The illustration shows how Z-scores in standard deviation units are marked out on either
side of the mean. It shows where your score sits in relation to the rest of the norm group.
If it is above the mean then it is positive, and if it is below the mean then it is negative.
As you can see from the illustration, Z-scores can be rather cumbersome to handle
because most of them are decimals and half of them can be expected to be negative.
T Scores (Transformed Scores)
T-scores are used to solve this problem of decimals and negative numbers. The T-score is
simply a transformation of the Z-score, based on a mean of 50 and standard deviation of
10. A T-score can be calculated from a Z-score using the formula:
T = (Zx10) + 50
Since T-scores do not contain decimal points or negative signs they are used more
frequently than Z-scores as a norm system, particularly for aptitude tests.
Stens (Standard Tens)
The Sten (standard ten) is a standard score system commonly used with personality
questionnaires. Stens divide the score scale into ten units. Each unit has a band width of
half a standard deviation except the highest unit (Sten 10) which extends from 2 standard
deviations above the mean, and the lowest unit (Sten 1) which extends from 2 standard
deviations below the mean.
Sten scores can be calculated from Z-scores using the formula: Sten = (Zx2) + 5.5.
Stens have the advantage that they enable results to be thought of in terms of bands of
scores, rather than absolute scores. These bands are narrow enough to distinguish
statistically significant differences between candidates, but wide enough not to over
emphasize minor differences between candidates.