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

Readings- Appendix B- Statistical Methods

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

Graphing Data

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

each score or group of scores (tally)

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

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

îDescriptive statistics: used to organize & summarize data

Measuring Central Tendency

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

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

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

mode

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

tendency

Measuring Variability

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

îSteps of calculating the standard of deviationî 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

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

human characteristics are dispersed in the population

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

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

ie. IQ test

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## Document Summary

Statistics: the use of mathematics to organize, summarize, & interpret numerical 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. 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. standard deviation: an index of the amount of variability in a set of data. steps of calculating the standard of deviation 1.