Psychological Assessment (Diagnosis) pt.2

Psychological Assessment

It is the gathering & integration of psychology-related data for the purpose of making a psychological evaluation.

Testing

It pertains to everything done from the administration, scoring and interpretation of the test.

Presenting concerns and purpose of evaluation.

In every psychological assessment, the assessor must first identify

Properties of Measurement

Property of Magnitude

Property of Equal Interval

Property of True Zero point.

Norm-referenced

Most IQ tests are:

Ratio

This is the level of measurement that has all the 3 properties of measurement and in which mathematical operations are most permissible

Nominal Scales

Ordinal Scales

Interval Scales

Ratio Scales

4 Levels of Measurement

Nominal Scales

Observation can be named but not placed in any order

Words, letters or number are used to classify the data

No mathematical operation applies

Zero is just a label

Ex. Sex (male of female), color (black, red, blue), brand of shoes

Nominal Scales

You can name but you cannot place them in order.

Example: A man is not taller than a woman, or the order of colors is...

Numbers can be used for labels, for example, in your research, 1 = female, 2 = male. However, this doesn't mean that males are ranked higher than females; the numbers are only used for labeling purposes.

None of the three properties of measurement exist (no magnitude (cannot rank it), equal intervals, and true zero point).

categorical

Nominal scales are often _____.

Ordinal Scales

Numbers can be ordered or arranged meaningfully from highest to lowest or vice versa

The interval or level are meaningful but not always equal

Median and percentile ranks may be employed

Ex. Top 10 (Top 1, Top 2, Top 3, etc.) Level of Satisfaction (Likert Scale)

Ordinal Scales

Numbers now have meaning.

The only property it has is the property of magnitude.

You know that top 1 is higher than top 2, and so on.

The Likert scale is considered ordinal (1, 2, 3, 4, 5 - it has an order).

However, ordinal scales do not have equal intervals.

Example: The top scorer in the board exam has a score of 89.60, the second has 88.60, and the third has 88.40— the intervals are not equal; the difference between top 1 and top 2 is one point, but the difference between top 2 and top 3 is only 0.2.

Ordinal Scales

In the Likert scale, the intervals may also not be equal. For example, a couple might both answer 2 on a love scale for the same statement, but we can't be sure if their "2" falls in the same range.

Some authors do not treat the Likert scale as an ordinal scale, and some treat it as an interval scale.

It does not have a true zero point.

Ordinal Scales

Every test taker, regardless of their standing or ranking in magnitude, is still assumed to have the ability being tested.

We can perform mathematical operations— such as median and percentile ranks.

Most psychological tests are ordinal in nature; however, we treat them as interval scales.

property of magnitude

The only property Ordinal Scales has is the ____.

ordinal scale

Some authors do not treat the Likert scale as an _____, and some treat it as an interval scale.

ordinal

Most psychological tests are ___ in nature; however, we treat them as interval scales.

Interval Scales

Indicates an actual amount (numerical)

The order and difference between the ranking can be known

Has no absolute zero point.

Mathematical operation (e.g., mean, SD, Person's R, Test of Significance) may be applied

Ex. Temperature (30 degree celsius, 20 degree celsius and 10 degree celsius, - 10 degree celsius)

Interval Scales

There are now two properties of measurement.

It has the property of magnitude: it can be arranged meaningfully in order.

It has the property of equal intervals: the difference between the rankings can now be known.

It now has equal intervals (e.g., there are degrees in between).

Interval Scales

However, it still does not have an absolute zero point or true zero point.

Celsius: it does not have an absolute zero point. Zero degrees Celsius does not mean there is no temperature—no cold or heat. In fact, with Celsius, we can even go beyond zero and into the negatives.

property of magnitude

property of equal intervals

Two properties of measurement of Interval Scales:

Property of Magnitude

means that the values have an ordered relationship to one another, so there is a specific order to the variables.

Property of Equal Intervals

mean that data points along the scale are equal, so the difference between data points one and two will be the same as the difference between data points five and six.

Property of True Zero

means the scale has a true zero point. Degrees, for example, can fall below zero and still have meaning. But if you weigh nothing, you don't exist.

Property of Magnitude

it can be arranged meaningfully in order.

Property of Equal Intervals

the difference between the rankings can now be known.

Ratio Scales

The order and difference can be described and has an absolute zero point and the ratio between two points has meaning

All mathematical operation can meaningfully be performed

Ex. weight (30 kg, 20 kg, 10 kg, 0 kg)

Ratio Scales

It has all the properties:

Property of magnitude.

Property of equal interval.

Property of true zero point.

It can also be ranked.

For example, one is at 50 km, the other is at 45 km.

Ratio Scales

Property of true zero point.

Example: Kilometers — in a race, you want to know how far you are from your competitor. It has an absolute zero point because if your competitor's recorded distance is 0 km, it means they didn't run or didn't start.

All mathematical operations can be used.

Central Tendency

A statistical measure to determine a single score that define the center of distribution

Central Tendency

Goal: find the single score that most typical or most representative of the entire group

In other words, this is the average value that can be used to describe the population

Central Tendency

A statistical measure we use to find or determine the single score that best describes the center of the distribution — or what single score we can use to describe the entire group because it is the most typical or average.

The average value that can describe our population or sample.

Mean, median, and mode are all averages because they represent central tendency — they are the single scores we can use to define the center of the distribution, to identify the most typical, most frequent, most average, or most representative value in our data set.

averages

Mean, median, and mode are all ____ because they represent central tendency — they are the single scores we can use to define the center of the distribution, to identify the most typical, most frequent, most average, or most representative value in our data set.

Mean

Median

Mode

Measures of Central Tendency

outliers

The median should be used if there is the presence of ____ — the average score is 15, but student A's score is 48, student B's score is 47, student C's score is 45, and student D's score is 46, all of which are far from the average of 15.

Mean

Average; sum of the observation or test scores divided by the number of observations of test scores

Mean

Appropriate for interval and ratio and when the distribution is approximately normal.

Median

If there is a presence of outliers, it is best to use

Median

Middle score in the distribution

Appropriate for: ordinal, interval and ratio.

Used when the distribution is skewed and when there are outliers.

Median

Appropriate for: ordinal, interval and ratio

Median

Used when the distribution is skewed and when there are outliers

Mean

Average; sum of the observation or test scores divided by the number of observations of test scores

Appropriate for interval and ratio and when the distribution is approximately normal.

Mean

To get the ___: you add or find the summation of the data set and then divide by (n), the number of data points.

Mean

We use the ___ when our data is continuous — when it is interval or ratio, and when the distribution is approximately normal.

normal

If the distribution is approximately ___, the mean accurately locates the center. Also, if the data is normally distributed, the mean, median, and mode are all equal.

skewed

However, if the distribution is ____ (e.g., positively skewed), the mean may not accurately locate the center because the presence of outliers may impact the mean. The extreme values or outliers may pull the mean away from the center.

Mean

The more skewed the distribution, the farther away the ____ will be from the center.

Mean

The ___ is sensitive to the presence of outliers

Median

Hence, when there is the presence of outliers, it is best to use the ___ instead of the mean.

In the mean, all the values in the data are incorporated.

If you change the data (e.g., make four values extremely high or low), the average or mean you obtain will change.

Mean

In the ___, all the values in the data are incorporated.