Psychological - W3 - Chapter 3 - DN Part 2
High kurtosis suggests more extreme outliers; low kurtosis suggests fewer.
kurtosis
an indication of the nature of the steepness of the centre of the distribution
i.e., peaked vs flat
p.97-98
Key Terms
kurtosis
an indication of the nature of the steepness of the centre of the distribution
i.e., peaked vs flat
p.97-98
leptokurtic
a description of the kurtosis of a distribution that is relatively peaked at its centre
linear transformation
in psychometrics
a process of changing a score such that
the new score has a direct numerical relationship to the original score
...
mean
a measure of central tendency
derived by calculating an average of all scores in a distribution
also called an arithmetic mean
p....
measurement
assigning numbers or symbols to characteristics of people or objects
according to rules
p.78-79
measure of central tendency
one of three statistics indicating the average or middlemost score between the extreme scores in a distribution
mean - ratio level
medi...
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| Term | Definition |
|---|---|
kurtosis | an indication of the nature of the steepness of the centre of the distribution i.e., peaked vs flat p.97-98 |
leptokurtic | a description of the kurtosis of a distribution that is relatively peaked at its centre |
linear transformation | in psychometrics a process of changing a score such that the new score has a direct numerical relationship to the original score the magnitude of the difference between the new score & other scores on the scale parallels the magnitude of differences on the scale from which it was derived contrast with nonlinear transformation p. 104 |
mean | a measure of central tendency derived by calculating an average of all scores in a distribution also called an arithmetic mean p. 89 |
measurement | assigning numbers or symbols to characteristics of people or objects according to rules p.78-79 |
measure of central tendency | one of three statistics indicating the average or middlemost score between the extreme scores in a distribution mean - ratio level median - ordinal (takes the order of scores into account) mode - nominal p.89 |
measure of variability | a statistic indicating how scores in a distribution are scattered or dispersed common measures of variability are range standard deviation variance p.92 |
median | a measure of central tendency derived by identifying the middlemost score in a distribution p. 89-91 |
mesokurtic | a description of the kurtosis of a distribution that is neither extremely peaked nor flat in its centre p.97 |
meta-analysis | a family of techniques used to statistically combine information across studies to produce single estimates of the statistics being studied p. 115 |
mode | a measureof central tendency derived by identifying the most frequently occurring score in a distribution p. 89, 91-92 |
negative skew | when relatively few scores fall at the lower end of the distribution negatively skewed exmination results may indicate the test was too easy some more difficult questions would better discriminate between scores at the higher end p.97 |
nominal scale | a system of measurement all things being measured are classified or categorised, based on one or more distinguishing characteristics placed into mutually exclusive & exhaustive categories p. 79-80 |
nonlinear transformation | in psychometrics a process of changing a score such that the new score does not necessarily have a direct numerical relationship to the original score, and the magnitude of the diffferences between the new score & the other scores on the scale, may not necessarily parallel the magnitude of differences of those from the original scale contrast with linear transformation p. 104 |
normal curve | bell-shaped, smooth, mathematically defined curve highest at the centre & gradually tapered on both sides - approaching but never touching the horizontal axis p. 85, 87, 98 |
normalized standard score scale | conceptually, the end product of "stretching" a skewed distribution into the shape of a normal curve usually through a non-linear transformation p. 104-106 |
normalizing a distribution | a statistical correction applied to distributions meeting certain criteria for the purpose of approximating a normal distribution thus making the data more readily comprehensible or manipulable p.104 |
ordinal scale | a system of measurement , where all things being measured can be rank-ordered the rank-ordering implies nothing about how much greater one ranking is than another no absolute zero point on the scale most scales in psychology & education are ordinal p. 80-81 |
outlier | an extremely atypical plot point in a scatterplot any extremely atypical finding in research p.111 |
Pearson r | a widely used statistic for obtaining an index of the relationship between two variables when that relationship is linear and the two correlated variables are continuous (i.e., can theoretically take any value) also known as the Pearson coefficient of product-moment correlation and the Pearson correlation coefficient |