Descriptive statistics: used to summarize the characteristics of a dataset
Measures of central tendency: mean, median, mode
Mean: average
Median: the middle number, or average of the middle two numbers
Mode: the most common number
Variability: range, variance, standard deviation
Range: max-min
Variance: how different the numbers are to their mean
Standard deviation (SD): the square root of variance (so it's basically the same thing)
Frequency distribution: (1) histogram (2) normal distribution = bell curve
Normal curve: +/- 1 SD is 68%; +/- 2 SD is 95%; +/- 3 SD is 99.7%
Percentile: the percentage of data below one data point (e.g. people scoring below you)
Skewness in graph Left/Negative skew: long tail to the left, mean < median < mode Right/Positive skew: long tail to the right, mean > median > mode