Psyc312-8

For which scales can a mean be calculated
- Nominal
- Interval
- Ratio
For which scales can a median be calculated
- Ordinal
- Interval
- Ratio
For which scales can a mode be calculated?
- Nominal
- Ordinal
- Interval
- Ratio
Advantages & Disadvantages of using the mean
- easily manipulated algebraically
- reliable because it takes into account every measure of a data set
greatly affected by extreme scores
Advantages & Disadvantages of Median
- little influence by extreme scores
- reasonable estimate of the center of a distribution
may not be good to ignore extreme values
Advantages & Disadvantages of Mode
not influenced by extreme scores
- may not represent the scores
- ignores extreme values completely
How to calculate IQR?
- Find the median location (n+1)/2
- Find quartile location (ML+1)/2
- Find Q1 & Q3 (low score + QL; high - QL)
- IQR= distance btwn Q3 - Q1
- Outliers: Q3+ (1.5 x IQR); Q1-(1.5 x IQR)
Empirical Rule...

68-95-99.7 within 3 standard deviations of the mean
Deviation

the difference btwn each score and the mean of the data set
Variance

single number representing the average amount of variation in a data set
Standard deviation

Measure of the spread of scores out from the mean of the sample

Author

ctryhurn

25285

Card Set

Psyc312-8

Description

psyc

Updated

2010-06-30T13:04:32Z

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