psychological assessment - l3

Discrete variable

It refers to data that can be directly counted

Continuous variable

This refers to data that are measured

Error

It refers to the collective influence of all of the factors on a test score or measurement beyond those specifically measured by the test or measurement

Nominal Scale

This is the simplest form of measurement and involves classification or categorization based on one or more distinguishing characteristics.

Ordinal Scales

This scale also permits classification, but it specifically employs rank ordering on some characteristics.

Interval Scales

This scale contains equal intervals between numbers, each unit on the scale is exactly equal to any other unit on the scale and contains no absolute zero point.

Ratio Scale

This scale has a true zero point, as all mathematical operations can meaningfully be performed because there exist equal intervals between the numbers on the scale as well as a true or absolute zero point.

Distribution

This may be defined as a set of test scores arrayed for recording or study

Raw Score

This is a straightforward, unmodified accounting of performance that is usually numerical

Frequency Distribution

This is when all scores are listed alongside the number of times each score occurred.

Graph

It is a diagram or chart composed of lines, bars, or other symbols that describe and illustrate data.

Histogram

It is a graph with vertical lines drawn at the true limits of each test score, forming a series of contiguous rectangles.

Frequency Polygon

This expresses the data by a continuous line connecting the points where test scores meet frequencies

Measure of Central Tendency

A statistic that indicates the average of midmost score between the extreme scores in a distribution

Arithmetic Mean

This is denoted by the symbol X-bar, and is equal to the sum of the test scores divided by the number of observations. (interval/ratio, normal distri)

Median

This is defined as the middle score in a distribution and is another commonly used measure of central tendency. (ordinal, interval, ratio)

Mode

This is the most frequently occurring score in the distribution of scores (quali/verbal data)

Variability

This is an indication of how scores in a distribution are scattered or dispersed

Range

This is equal to the difference between the highest and the lowest scores, and is the simplest measure of variability to calculate.

Skewness

The lack of symmetry in a data distribution, where one stretches further from the center than the other.

Kurtosis

This refers to the steepness of a distribution in its center

Normal Curve

This is theoretically defined as a bell-shaped, smooth, mathematically defined curve that is highest at its center. It is perfectly symmetrical, with no skewness.

Standard Score

It is a raw score that has been converted from one scale to another scale, where the latter has some arbitrarily set mean and standard deviation