Transcript Definition of Test

Chapter 4: Test administration
z scores
 Standard score expressed in terms of standard deviation units




which indicates distance raw score is from mean.
z scores can be positive (score above mean) or negative (score
below mean)*
A z score of 0 is the mean
z= X-X or
X-X *
s
s
* occurs when the better score is lower than the mean (golf,
time in a race, percentage of body fat)
Let’s try it:
 You have a set of scores for the long jump and the mean is 50
with a standard deviation of 5. What would the z score of the
score 42 be? How about 55?
 How about this one: you have a set of golf scores with a mean
of 10 and a standard deviation of 2. What would the z score
of the score 12 be? How about 7?
T scores
 Derived from a z score
 Will always be a positive whole number with a T score of 50
representing the mean
 Easier for some to comprehend since it is on a scale of 0-100
 T= 10z +50
 or 10 (x-x) +50
s
So, can you calculate a T score from a -2.4 z score?
How about from a z score of +3.7?
z and T scores
 z scores have a standard deviation of 1 with a mean of 0
 T scores have a standard deviation of 10 with a mean of 50
 So, a +1 z score = a T score of 60; a -2 z score = a T score of
30
 Since we know that when scores are normally distributed
that 99.7% of all scores will fall between a standard deviation
of +- 3, we rarely have a T score above 80 or below 20
 We can also so that a score at the 84th percentile is equal to a
z score of +1 and a T score of 60. Why?
Correlation
 Relationship between two variables
 Correlation coefficient is the statistic that indicates the
relationship or association between variables
 Correlation does not mean cause and effect
 You could compare the relationship between height and
weight for a group of students (+ correlation)
 You could compare speed in the 100 meters and long jump
(inverse correlation)
Correlation Coefficients
 With a positive correlation the change of direction of both




variables will be the same (either both increase or decrease)
With an inverse correlation the change of direction of one
variable increases as the other decreases
The degree of correlation or relationship is determined by a
number from -1.00 to +1.00
The higher the number regardless of sign, the more closely
related the variables
The lower the number regardless of sigh, the less closely
related the variables
Rules to remember
 Correlation coefficients fall between +- 1.00
 The sign of a correlation coefficient indicates type of
relationship (positive or inverse)
 +- .80- 1.00= high relationship
 +- .60-.79 = Moderately high relationship
 +- .40-.59 = Moderate relationship
 +- .20- .39 = Low relationship
 +-0-.19 = no relationship
 +.75 and -.75 indicate the same degree of relationship but
one is positive and one is inverse
Correlational Procedures
 Pearson Product Moment Correlation
…..requires interval or ratio data
 Spearman Rho Rank Order Correlation
…..requires ordinal data
Definition of Test
Test – an instrument, protocol, or technique used to measure a
quality or quantity of properties or attributes of interest.
Can you give an example of a test from each domain?
Critical Test Criteria
 Test Objectivity – type of reliability related to the
administration of the test
 Test Reliability – consistent, repeatable results
 Test Validity – accurately measures the attribute that the test
is designed to measure
Establishing Objectivity
 Teacher must understand the test.
 Teacher must administer test appropriately – follow
protocols.
 Students must understand how test is performed and how it
is scored.
There is no substitute for common sense in measurement and
evaluation!
Establishing Reliability
 Test – Retest Reliability
 Alternate Form Reliability
 Split Half or Odd-Even Reliability
Which method is typically used in tests that require physical
performance?
Establishing Validity
 Face Validity
 Content Validity
 Construct Validity
 Concurrent Validity
 Predictive Validity
Which of these presents the strongest rationale for validity?
Relationship of Validity, Reliability, and
Objectivity
 Without objectivity, an instrument will lack reliability.
 A test may be reliable but not valid.
 Without reliability, a test cannot be valid.
Therefore, objectivity is a prerequisite for reliability, and reliability is a
prerequisite for validity.
Administrative Concerns
in Test Selection
 Relevance
 Educational Value
 Economy
 Time
 Enjoyment
 Availability of Norms
 Discrimination
Administrative Concerns in Test
Selection (continued)
 Independence
 Gender Appropriateness
 Reliance on Another’s Performance
 Safety
 Testing Large Groups
 Ease of Scoring, Interpreting, and Reporting
Planning Test Administration
 Know the test.
 Prepare the test area.
 Train testers (assistants).
 Warm up for physical activity tests.
 Standardize instructions.
 Practice test items.
 Record scores efficiently.
 Interpret and evaluate the results.