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Measure of Spread - Data Analysis in Psychology - Lecture Slides, Slides of Advanced Data Analysis

Measures of Spread, Highest Score, Distance From the Lowest, Problem of Clustering Differences, Problem of Outliers, Interquartile Range, Effect of Extreme Scores, Trimmed Samples, Loss of Information, Average Deviations. These are the important points of Psychology.

Typology: Slides

2012/2013

Uploaded on 01/01/2013

sarman
sarman 🇮🇳

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Measures of Spread
1. Range: the distance from the lowest to the highest score
* Problem of clustering differences
** Problem of outliers
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Measures of Spread

  1. Range: the distance from the lowest to the highest score
  • Problem of clustering differences

** Problem of outliers

  1. Interquartile Range
  • omits the upper and lower 25% of scores
  • eliminates the effect of extreme scores
  • trimmed samples
  • loss of information

Data Set I:

8, 8, 9, 10, 11, 11, 12, 12, 12, 12, 12, 13, 13, 13, 14,14, 15, 15, 16, 17

Range = 9 Interquartile Range = 3

Data Set II:

1, 2, 3, 10, 11, 11, 12, 12, 12, 12, 12, 13, 13, 13, 14,14, 15, 21, 25, 30

Range = 29 Interquartile Range = 3

Variance:

Standard

Deviation:

These are here defined as descriptive statistics.

average of the summed, squared-deviations about the mean

n

y y

s y

2 2

the square root of the average of the summed squared deviations about the mean

n

y y

s y^ ∑^

2

As inferential statistics

2 2

n

y y

s y

2

= ∑^

n

y y

s y

See the difference