NAME: ________________________

← Reuschling's Second ExamTest

Question Limit

of 40 available terms

5 Matching Questions

1. standard deviation
2. computing the S.D.
3. ratio scales (#4, most complex---four properties)
4. types of variables: discrete
5. quartiles
1. a measures of variability that divide the distribution of scores into four quarters.
(pgs 48-49)
GOOOOOOOOOOSH... this stuff blows my brain into tiny bits. I am praying this part isn't on the exam!!!!
2. b have properties of identity, rank order, distance between numbers AND "additivity"
"additivity" means they can be added, subtracted, multiplied, divided... with meaningful results.

ratio scales have a zero point (see pg 41 for this... I don't get it... lol) This means that it measures things that start at zero. (spead for example, or money- you can have zero money in your account so a measure could be 0 to 5,000 to 10,000 and so on).
3. c The square root of the variance. If the variance is 6.5, the SD is 2.55. It is the quintessential measure of variability for testing.
4. d you can estimate the S.D. by taking the range of scores and dividing by 6 (the approximate number of standard deviations in a normal curve); e.g.,
high score = 76, low score = 10, range = 66
standard deviation (estimated) = 11
5. e discrete variables have a finite range of values.
discrete variables are dichotomous if there are only 2 values possible (you will have a boy or a girl. You will flip heads or tails on a coin.)
discrete variables are polytomous if more than 2 values are possible (rolling dice, you could roll any value 2-12)
*in principle, discrete variables can be counted precisely without error.

5 Multiple Choice Questions

1. ("the tail is the clue to the skew")
long tail pointing in the positive direction: positively skewed
long tail pointing in the negative direction: negatively skewed
2. +1 S.D. = 84th percentile ("in a room of 100 people, about 16 will score higher")
+2 S.D. = 97th percentile
+3 S.D. = 99th percentile
-1 S.D. = 16th percentile ("in a room of 100 people, about 84 will score higher")
- 2 S.D. = 3rd percentile
- 3 S.D. = 1st percentile
3. mean (statistical average)
median (lands in the middle of all scores listed in numerical order)
mode (most frequently occurring value in a distribution)
4. the distance between the highest value in the bottom quartile and the highest value in the third quartile, thus covering the middle fifty percent of a distribution
5. bell shaped
bilaterally symmetrical with each half containing 50% of the area under the curve
tails approach but never touch the baseline (thus extends to ± infinity)
unimodal (a single point of maximum frequency or maximum height-- ONE MODE.)
mean, median, mode coincide at the center of the distribution

5 True/False Questions

1. Variation and the "standard deviation" (S.D.)The square root of the variance. If the variance is 6.5, the SD is 2.55. It is the quintessential measure of variability for testing.

2. ordinal scales (#2--two properties)also known as equal-unit scales
they have the properties of identity, rank order AND the distance between numbers
(ex: see page 40 for an example about minutes and hours and days that is too complicated for me to rephrase... lol)

3. variability"the degree to which the scores in a sample differ from each other or, as more commonly expressed, differ from the mean of the sample" (Penguin Dictionary of Psychology)

4. value of the normal curvethe most prominent probability distribution in stats
used throughout the natural and social sciences as a simple model for complex phenomena
user-friendly analytically (i.e., a large number of results can be derived from it)
based on the "central limit theorem" (i.e., under mild conditions a large number of random variables are distributed approximately normally)
"bell" shape makes it convenient for modeling a large variety of real world variables

5. Kurtosis: score variabilityKurtosis refers to the degree to which scores cluster about the mean (i.e., degree of variability in scores)
A normal curve (or distribution or variability of scores) is mesokurtic
Two other possibilities, platykurtic distributions and leptokurtic distributions