Understanding the Normal Curve and z Scores

Squared Deviations

Sum of squared differences from the mean

Mean

Average value of a set of numbers

Standard Deviation

Measure of the amount of variation or dispersion of a set of values

Z Score

Number of standard deviations a data point is from the mean

Variance

Average of the squared differences from the mean

Population

Entire group being studied

Sample Size

Number of observations in a sample

Percentile

Percentage of scores that fall below a specific value

Normal Distribution

Symmetrical bell-shaped curve representing a distribution of data

Standard Normal Distribution

Normal distribution with a mean of 0 and standard deviation of 1

Percentiles

Measure of relative standing within a dataset

Google Ngram

Tool to analyze word usage frequency in literature over time

Standardization

Process of transforming data to have a standard scale

Central Limit Theorem

States that the distribution of sample means approaches a normal distribution as sample size increases

Distribution of Means

Comprised of averages calculated from all possible samples of a given size from the same population