Statistical Definitions To Study For First Exam

Front 1

Define inference.

Back 1

An inference is simply a deductive analysis.

Front 2

What types of studies gather information about validity?

Back 2

Validation studies.

Front 3

What is Psychological Assessment?

Back 3

A purposive, data-gathering enterprise that defies description. Procedures change depending on what you are gathering.

Front 4

What is Psychological Testing?

Back 4

A process of measuring psychologically related variables by means, devices, or procedures designed to obtain a sample of behavior.

Front 5

How does the structure of an interview increase reliability?

Back 5

To approach the interview the same way each time, increases ability to make an evaluation and boosts reliability.

Front 6

How does behavioral observation evolve as you learn how to assess clients?

Back 6

You learn to interview objectively, keep behavioral observations clear, and teach clients to problem solve.

Front 7

What is a good test?

Back 7

One that:
is reliable, valid, and has norms.

Front 8

History of Statistics: Talk about Darwin, Freud, and Galton.

Back 8

They did research on heredity and devised the (correlation of coefficient or how things correlate). This helped to identify specific aspects of personality, abilities, etc. and to see how things correlate.

Front 9

History of Statistics: Talk about Binet.

Back 9

1890’s Binet and school system in France...developed intelligence test to see who may have difficulty learning...measured memory, judgment, and perceptual acuity.

Front 10

History of Statistics: Talk about Leipzig, Germany.

Back 10

Leipzig U. Germany...experimental psychology began...description of human ability, memory, reaction time formulated...people same, not different.

Hint 10

Research was sensitive to different variables that could affect what is observed….light, environment, cold, etc. People reacted differently.

Front 11

History of Statistics: Talk about early testing.

Back 11

American Philosophers studied at Liepzig...
publication in 1890. Binet? founded Psych Corp…largest seller of Psych tests...became important to look at reliability, and validity.

Hint 11

Most of the testing of the 1800’s involved sensory abilities (reaction time,) allowed for processing with the help of the brain. Published by Binet in 1905 and launched the whole field of psychological testing.

Front 12

What is Personality Testing? How did it come about?

Back 12

WWI created need for personality testing...placement on the battlefield. Self-reports...little reliability/validity. In WWII it was expanded and became much more sophisticated.

Hint 12

But, no way to predict what a person will do in combat. PTSD stories, faces, body language tell. Psych testing can help but not perfect. On the field tells the tale.

Front 13

What is Statistics?

Back 13

Things that underlie testing. Measurement is the act of assigning numbers (Mild, moderate, severe) to characteristics of objects (depression) according to different rules (on how to administer, interpret, test).

Front 14

What is Measurement?

Back 14

Measurement is the act of assigning numbers….

Hint 14

There are also different scales: continuous or discrete.

Front 15

What is the difference between Discrete scales and Continuous scales of measurement?

Back 15

Discrete scales are not helpful (male or female, age…don’t give much information about person). Continuous (contains error) scale used most frequently in Psychological Testing.

Front 16

Key to Psychological Testing is wrapped up in one important concept. What is that concept?

Back 16

Key: Nothing in Psych Testing is perfect. Numbers on a continuous scale contains error. We will never come up with a real score.

Hint 16

Ex. 97 is not a true IQ score because of error. +-5 makes the true score between the range of 92 and 102. We will never get a true score.

Front 17

Explain the concept of error.

Back 17

Any factor entering into process that is not directly relevant to whatever we are measuring. Ex. administrator has bad day or goes too quickly. Minimize difficulties person will be facing.

Hint 17

A test instructor is required to come up with a standard error range. We take the client’s score and add/subtract the range.

Front 18

Describe the four major scales.

Back 18

Nominal, ordinal, interval, ratio, (NOIR means black in French)

Front 19

Describe a Nominal Scale.

Back 19

It classifies and categorizes. Ex. Male/female…mutually exclusive not used in psychological testing. The DSM classifies and catagorizes.

Hint 19

DSM is useful but not in testing.

Front 20

Describe an Ordinal Scale.

Back 20

Ordinal allows classification and ordering and also rank ordering, (Olympic figure skating)...problems with consistency...no absolute zero...most often used scale in psych. testing.

Hint 20

IQ is here because it contains rank ordering. We compare scores to the bell curve. The further away from the mean the more significant in the way of how persons’ function. Examples: Weschler, Stanford Binet, etc.

Front 21

Describe an Interval Scale.

Back 21

Has equal intervals and no absolute zero. Each interval is exactly equal to all intervals on that scale.

Hint 21

Ex. A thermometer has intervals of 1 degree, 1 degree, 1 degree, and -1 degree, -1 degree, etc.

Front 22

Describe a Ratio Scale.

Back 22

Ratio has all properties of other scales with a true zero. Often used in chemistry, physics, medical tests. Do not use in psychological tests.

Front 23

History of Statistics: Talk about Darwin, Freud, and Galton.

Back 23

Repetitive...ignore

Front 24

History of Statistics: Talk about Binet.

Back 24

Repetitive...ignore

Front 25

History of Statistics: Talk about Leipzig, Germany.

Back 25

Repetitive...ignore

Front 26

History of Statistics: Talk about early testing.

Back 26

Repetitive...ignore

Front 27

What is Personality Testing? How did it come about?

Back 27

Repetitive...ignore

Front 28

Describe the four major scales.

Back 28

Repetitive...ignore

Front 29

Describe a Nominal Scale.

Back 29

Repetitive...ignore

Front 30

Describe an Ordinal Scale.

Back 30

Repetitive...ignore

Front 31

Describe an Interval Scale.

Back 31

Repetitive...ignore

Front 32

Describe a Ratio Scale.

Back 32

Repetitive...ignore

Front 33

Why are intelligence, aptitude, and personality test scores basically and strictly speaking ordinal?

Back 33

They indicate with more or less accuracy not the amount of intelligence, aptitude and personality traits, but rather the rank order and position of individuals.

Hint 33

You may be 100 but many people are also 100 and not one of them is the same as the other.
The main thing is the standard of error. People have spent their entire careers trying to define self-esteem, personality, etc. We never come up with a true score but we can come up with a range.

Front 34

How are test results communicated?

Back 34

One way is a frequency distribution. All possible scores are listed with all the times each score occurred. 200 people = 200 IQ scores. One way to measure this is to measure how often they occur. The average score is supposed to be 100, we can assume that most numbers occur around 100, with less above and less below.

Hint 34

In the textbook we see how these are done. Ex. Bar graph. This leads to the ways to interpret tests and say what the results mean. Distributions can determine central tendency (mean, median, mode) and variability. Mean is most appropriate measure of central tendency, however the book on page 28 says that the mode, median, and mean are all measures of central tendency.

Front 35

Explain the Bell Curve.

Back 35

Bell Curve: See p. 31 for picture, fig. 2.3 -- These numerical operations are used by all test instructors. When 100 is the most often IQ score. SD = 15, then 115 is one standard deviation above the mean. This is all based on the Bell shaped curve. The middle is the mean. If we add the sliced sections to the right it will be labeled +1, +2, +3, and to the left is -1, -2, -3 etc. If the SD is 15, then you add or subtract the SD from the score of 100 to determine your clients score. Because of the concept of the Bell Curve, the mean is 15, however, in personality it is 50. The key word is deviates. How a person deviates from the norm.

Front 36

Explain Analysis of Variance.

Back 36

Analysis of variance analyzes variability among tests. This helps us to understand how things are correlated. We not only look at how are things the same, but also how they vary or differ.

Front 37

Bell Curve explained with regard to how scores vary from one another.

Back 37

From this perspective, (bell curve where 100 is the most frequent score and 15 is SD) 68% of population falls between -1 and +1. (34 + 34). 96% falls between -2 and +2 (14 + 14 more). We are classifying people, rank ordering people so it’s an ordinal scale. If someone comes up with an IQ score of 70, we can say for example, that approx. 95-97 % of the other individuals will score more than 70. So we are classifying them and rank ordering them to understand that there are a large number of individuals with greater intellectual abilities than them. On the converse, they are more intellectually endowed than 2-3 % of the population. We always start with the mean or the average. This is a form of number communication that does not have to be a mystery. Keep in mind the measurement of error (range). Everything rests on Bell shaped curve. Key is mean and SD. Range of numbers across the curve: -1, 2, 14, 34, 34, 14, 2, 1. SD is 15. On another note, the larger sample and wider range of abilities tested the closer the curve will approximate the normal bell curve. In other words, the more people you test the better you’ll approximate the general population.

Front 38

Definitions and Symbols: Mean

Back 38

Mean (M) is just the average of the scores. Take all scores, add, divide by amt. of people and you have the mean.

Front 39

Definitions and Symbols: Median

Back 39

Median is what is called the middle score of the distribution (what is between the lowest and highest score),

Front 40

Definitions and Symbols: Mode

Back 40

Mode is the most frequently occurring score

Front 41

Definitions and Symbols: Variability

Back 41

Variability is an indication of how scores in a distribution are scattered or disbursed. It can be a narrow or wide range between highest and lowest score.

Hint 41

Low 25, high 75 = range 25-75. One of the most important aspects of variability is called standard deviation.

Front 42

Definitions and Symbols: Standard Deviation

Back 42

Standard Deviation is a measure of variability. It is the square root of the variance.

Hint 42

Come up with distribution. Calculate mean = 100. Take all scores and subtract the mean. 101 would be +1. 129 would be +29. Now take those scores and do the square root of those scores and you get standard deviation. How does my score deviate from the mean?

Front 43

Definitions and Symbols: M

Back 43

M = Mean

Front 44

Definitions and Symbols: X

Back 44

X = Score

Front 45

Definitions and Symbols: Greek symbol that looks similar to an E

Back 45

E = to sum

Front 46

Definitions and Symbols: N

Back 46

N = number of individuals in group

Front 47

Definitions and Symbols: SD

Back 47

SD = standard deviation

Front 48

Definitions and Symbols: Multimodal

Back 48

Multimodal = when scores do not fall into a normal distribution (distribution with more than one peak)

Front 49

Definitions and Symbols: Skewed

Back 49

Skewed = majority of people score in low range or high range (as compared with normal distribution)

Front 50

Definitions and Symbols: Positively skewed

Back 50

Positively skewed = majority of scores are at lower end of distribution (opposite of what makes sense}.

Hint 50

However, when you consider that the mean is skewed positively when the scores are mostly lower, it does make sense)

Front 51

Definitions and Symbols: Negatively skewed

Back 51

Negatively skewed = majority of scores are at higher end of distribution (opposite of what makes sense, however, when you consider that the mean is skewed negatively when the scores are mostly higher, it does make sense)

Front 52

Definitions and Symbols: Percentile Rank

Back 52

Percentile rank = can be determined for any distribution of scores, not just for normalized distributions. To find the percentile, we first have to determine how many people out of the group had each score, and then we calculate the percentage of people out of the total group who received that score. For example, for the score of 60, we can see that four people received that score, and 4 divided by the total group of 25 is equal to 16%. As stated earlier, percentiles are the percent of people who received a score at or below a given raw score. Therefore, to get percentiles, we add the percentage of people who had a score at or below each of the raw scores. To continue (table 2.4, p. 33) add the percentage of people at each score that are at and lower than 60 (4+8+8+20+24+16=80). In interpreting your score of 60, a counselor might say, “Eighty percent of the norming group had a score at or below yours.” Another example would be I have a score of 50. Six (6) people had a score of 50, and 6 divided by the total group of 25 is equal to 24%. Now, to get percentile, we add the percentage of people who had a score at or below 50 (4+8+8+20+24=64). In interpreting your score of 50, a counselor might say, “Sixty-four percent of the norming group had a score at or below your score.”

Front 53

Definitions and Symbols: Percentile Rank

Back 53

Percentile rank = can be determined for any distribution of scores, not just for normalized distributions. To find the percentile, we first have to determine how many people out of the group had each score, and then we calculate the percentage of people out of the total group who received that score. For example, for the score of 60, we can see that four people received that score, and 4 divided by the total group of 25 is equal to 16%. As stated earlier, percentiles are the percent of people who received a score at or below a given raw score. Therefore, to get percentiles, we add the percentage of people who had a score at or below each of the raw scores. To continue (table 2.4, p. 33) add the percentage of people at each score that are at and lower than 60 (4+8+8+20+24+16=80). In interpreting your score of 60, a counselor might say, “Eighty percent of the norming group had a score at or below yours.” Another example would be I have a score of 50. Six (6) people had a score of 50, and 6 divided by the total group of 25 is equal to 24%. Now, to get percentile, we add the percentage of people who had a score at or below 50 (4+8+8+20+24=64). In interpreting your score of 50, a counselor might say, “Sixty-four percent of the norming group had a score at or below your score.”

Front 54

Definitions and Symbols: Percentile Bands

Back 54

Percentile Bands = relate to the above percentile rank and are used on Armed Services Aptitude Battery based on standard error of measurement (see Chap. 3). Percentile Bands are useful because they can show a range of where clients could expect their scores to fall if they took the instrument multiple times.

Front 55

Definitions and Symbols: Random Sample

Back 55

Random Sample = a sample of the larger population where every member has an equal chance of being selected. However, it is hard to gather this wide of a sample.

Front 56

Definitions and Symbols: Stratified Sample

Back 56

• Stratified Sample = sample drawn from larger population based on certain demographic characteristics. US Census reports are consulted to make sure the percentage of individuals in the smaller sample match the percentages of individuals in the larger population.

Front 57

Definitions and Symbols: Cluster Sampling

Back 57

Cluster Sampling = randomly selected larger units of all (elementary schools, hospitals, etc.)

Front 58

Definitions and Symbols: Criterion Referenced

Back 58

Criterion Referenced: To compare an individual’s performance with an established standard or criterion.

Front 59

Definitions and Symbols: Norm Referenced

Back 59

Norm Referenced: To compare an individual’s performance with other people’s performance on the instrument.

Front 60

Different kinds of scores: Raw Score

Back 60

Raw Score: the simplest of the scoring methods which is meaningless without any other interpretive data. Raw scores are those that have not been converted to another type of scoring (e.g., percentile, T score). On the CAS assessment, my score of 60 means nothing until we begin to examine the distribution of scores, measures of central tendency, and measures of variability. When we examine these indicators, we typically have more information with which to interpret a score. Sometimes, however, we want additional information concerning how an individual performed in comparison with the norming group. This is accomplished by converting the raw score to a percentile rank, or percentile score

Front 61

Different kinds of scores: Percentile Rank or Percentile Score

Back 61

Percentile Rank or Percentile Score: a person’s rank on the distribution. If Mary had a score of 68, then out of 100 people taking the test, 68 of them would have a score at or below Mary’s score. Remember: we calculate the percent of people who received a score at or below a given raw score, (an ordinal scale and cannot be analyzed using statistics that require interval data, p. 34…line just above fig. 2.5). Standard Scores address the limitation of unequal units of percentiles, while providing a “shorthand” method for understanding test results (p. 35 top).

Front 62

Different kinds of scores: Standard Score

Back 62

Standard Score: a standard score has a mean of 100 and a SD of 15. Raw score that has been converted from one scale into another scale, the latter scale being more widely used and interpretable. Ex. There is a test of 30 items making possible score of 60. Person gets a 45. Raw score of 45 means nothing. You must convert to scale score which is a 12. It fits into the 1-19 distribution with 9/10/11 being the mean. So the 12 signifies average. Now the raw score is converted into something meaningful. What we are talking about is how to communicate information by the use of numbers. The numbers do the talking for us. They give us a basis for how to talk about a person. They can be ranked with others and describe how many standard deviations a client’s score is from the mean (p. 35 Standard Scores).

Front 63

Different kinds of scores: T Score

Back 63

T Score: Primarily used for personality tests, MMPI, etc. Mean is 50 and SD is 10

Front 64

Different kinds of scores: A Score

Back 64

A Score: Mean is 500 SD is 100. SAT’s are A scores

Front 65

Different kinds of scores: Z Score

Back 65

Z Score Formula:
z = X – M over s (could not write equation in this flashcard format)
See Table 2.5 p. 35

Front 66

Talk about WWI and need for assessment.

Back 66

The advent of WWI created a need to do psych assessment. They used it to know where to place soldiers. This was even more important in WWII.

Front 67

Talk about WWII and need for assessment.

Back 67

They first give an exam before and after basic training to determine the areas a soldier would be best suited for. Ex. Submarines stay under water now for six months. This is an example of ability testing.