Statistics Basics
Interpret summaries and reports more accurately.
alternative hypothesis
the statement that there is a significant effect or relationship
z-score
the number of standard deviations a data point is from the mean
bias
a systematic error that results in an unrepresentative sample
Type I error
rejecting a null hypothesis that is actually true (false positive)
Type II error
failing to reject a null hypothesis that is actually false (false negative)
Central Limit Theorem
the theory that the distribution of sample means approaches a normal distribution as sample size increases
p-value
the probability of obtaining results at least as extreme as the observed results, assuming the null hypothesis is true
confidence interval
a range of values likely to contain the true population parameter
normal distribution
a symmetric, bell-shaped frequency distribution
regression
a statistical method for estimating the relationships between a dependent variable and one or more independent variables
sampling error
the difference between a sample statistic and the actual population parameter
correlation
a measure of the linear relationship between two variables
population
the entire group of individuals that is the subject of study
sample
a subset of a population used to represent the whole
probability
the likelihood that a specific event will occur
null hypothesis
the assumption that there is no effect or relationship
range
the difference between the highest and lowest values
standard deviation
a measure of how spread out numbers are from the mean
outlier
a data point that differs significantly from other observations
variance
the average of the squared differences from the mean
skewness
a measure of the asymmetry of a probability distribution
mode
the most frequent value
median
the middle value in an ordered list
mean
the arithmetic average