Involves the application of specific procedures for assigning numbers to objects. Each measurement value is represented in the form of some standard units, i.e., time, temperature, weight, length etc. The estimated values by these measurements are actually compared against the standard quantities that are of same type.

A measurement scale in which numbers serve only as labels and do not indicate a quantitative relationship. Classifying by name based on characteristics of the person or object being measured.

Provides a measure of magnitude, and makes it possible to determine which scores are smaller or larger than other scores. Also enables one to rank or order individuals or objects.

Units are in equal intervals. A measurement scale in which equal differences between nunbers represent equal differences in the thing measured. The zero point is arbitrarily defined.

A ratio scale has all the properties of an interval scale, except the interval scale requires the existence of a meaningful zero. Such as measuring pulse, or liquid ounces, height, & weight.

A norm-referenced instrument is one in which an individual's performance is compared with the performance of other individuals who have taken the same instrument.

With a criterion-referenced instrument, the interest in not on how the individual's performance compares with the performance of others, but rather on how the individual performs with respect to some standard or criterion. Example: Does Lisa spell 90% of fifth-grade spelling words correctly?

The score that occures most frequently in a distribution. To find the mode, you count the number of people who received each score, and the score withthe highest number of people is the mode. Example: On the midterm exam, the mode is 90 because nine out of 15 people received the score of 90.

The point that divides a distribution of scores into equal halves; half the scores are above the median and half are below it. The 50th percentile.You find the median by arranging the scores in order from lowest to highest and finding the middle number. If the distribution is comprised of an odd number of participants, then median is:

N + 1

2

The arithmetic average; the sum of the scores divided by the number of scores:

μ = ∑ƒΧ

   N

Deviation just means how far from the normal;

A descriptive measure of the dispersion of scores around the mean of the distribution. This provides an indication of the average deviation from the mean in the original unit of measurement.

The Standard Deviation is a measure of how spread out numbers are.

Its symbol is σ (the greek letter sigma)

The formula is easy: it is the square root of the Variance

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The average of the squared differences from the Mean. Do this by adding the scores together and divide by the number of scores

Raw scores are scores that have not been converted to another type of scoring (e.g., percentile, or T-scores).

Sample refers to the group that is actually being sampled. It is the subset of a population, that may or not be representative.

All measurements of a specified group. A population consist of all the scores of some specified group.

Reliability refers to the consistency of a measure. A test is considered reliable if we get the same result repeatedly. For example, if a test is designed to measure a trait (such as introversion), then each time the test is administered to a subject, the results should be approximately the same.

Cronbach's α (alpha) is a coefficient of reliability. It is commonly used as a measure of the internal consistency or reliability of a psychometric test score for a sample of examinees. It was first named alpha by Lee Cronbach in 1951, as he had intended to continue with further coefficients. The measure can be viewed as an extension of the Kuder-Richardson Formula 20 (KR-20), which is an equivalent measure for dichotomous items.

Cronbach's α is defined as

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where K is the number of components (K-items or testlets), [image] the variance of the observed total test scores, and [image] the variance of component i for the current sample of persons.

In theory, these are easy to distinguish — an action or occurrence can cause another (such as smoking causes lung cancer), or it can correlate with another (such as smoking is correlated with alcoholism). If one action causes another, then they are most certainly correlated. But just because two things occur together does not mean that one caused the other, even if it seems to make sense.

Validity is the extent to which a test measures what it claims to measure. It is vital for a test to be valid in order fo the the results to be accurately applied and interpreted.

Two forms of an instrument that can be correlated; resulting in an estimate of reliability.

Individuals are given one form of the instrument initially, and assessessed with an alternate/parallel form of the instrument.

Alternative assessment gives instructors a way to connect assessment with reveiw of learning strategies.

Differential item functioning (DIF) occurs when people from different groups (commonly gender or ethnicity) with the same latent trait (ability/skill) have a different probability of giving a certain response on a questionnaire or test.^[1] DIF analysis provides an indication of unexpected behavior by item on a test. An item does not display DIF if people from different groups have a different probability to give a certain response; it displays DIF if people from different groups of same underlying true ability have a different probability to give a certain response. More precisely, an item displays DIF when the difficulty level (b), the discrimination (a) or the lower asymptotes (c) – estimated by item response theory (IRT) – of an item differs across groups. Thus, when one or more item parameters differ across groups, an item displays DIF.

A table listing all classes and their frequencies arranged from lowest to highest score

In statistics, a frequency distribution is an arrangement of the values that one or more variables take in a sample. Each entry in the table contains the frequency or count of the occurrences of values within a particular group or interval, and in this way, the table summarizes the distribution of values in the sample.

The characteristic curve obtained by plotting a graph of a normal distribution, and is shaped like a bell.

In probability theory, the normal (or Gaussian) distribution is a continuous probability distribution that is often used as a first approximation to describe real-valued random variables that tend to cluster around a single mean value. The graph of the associated probability density function is "bell"-shaped, and is known as the Gaussian function or bell curve:

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A

percentile

score, more commonly referred to as a percentile rank, represents the percentage of people in a group who scored at or below any given raw score.

The percentile rank tells the counselor the percent of scores equal to or below the score they are investigating.

Mathematically, a percentile rank (

PR) equals the cumulative frequency (cf ) that corresponds to a given (X

) score (in this  case, the one for which you are trying to find the percentile rank) divided by the number (N

) of people in the frequency distribution and then multipliedby 100. The formula looks like this:

PR

= cf / N × 100