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Chapter

# PSYC 1010 Chapter Notes -Standard Deviation, Frequency Distribution, Descriptive Statistics

by OneClass9773

3 pages118 viewsFall 2010

This

**preview**shows half of the first page. to view the full**3 pages of the document.**Readings- Appendix B- Statistical Methods

Statistics: the use of mathematics to organize, summarize, & interpret numerical data

Graphing Data

Frequency distribution: an orderly arrangement of scores indicating the frequency of

each score or group of scores (tally)

Histogram: a bar graph that presents data from a frequency distribution

Frequency polygon: a line figure used to present data from a frequency distribution

Descriptive statistics: used to organize & summarize data

Measuring Central Tendency

Negatively skewed distribution: most scores pile up at the high end of the scale

Positively skewed distribution: scores pile up at the low end of the scale

A few extreme scores at one end pull the mean, & slightly the median, away from the

mode

Mean may be misleading & the median usually provides the most accurate central

tendency

Measuring Variability

Standard deviation: an index of the amount of variability in a set of data

Steps of calculating the standard of deviation 1. Add scores & divide by the

number of scores to calculate the mean. 2. Calculate each scores deviation (subtract

the mean from each score). 3. Square these deviations from the mean & total the

results. 4. Insert the numbers into the formula & complete the results. Formula=

square root of total deviation squared, divided by the number of scores.

The Normal Distribution

Is the symmetrical, bell-shaped curve that represents the pattern in which many

human characteristics are dispersed in the population

When a trait is normally distributed, most scores fall near the centre (the mean)

Normal distribution is a precise way to measure how people compare to one another

ie. IQ test

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