Estimating population parameters from sample statistics The characteristics of samples and populations are described by numbers called statistics and parameters: A statistic is a measure that describes the…
Descriptive versus inferential statistics Descriptive statistics allow you to describe a data set, while inferential statistics allow you to make inferences based on a data set. Descriptive statistics Using descriptive statistics, you…
How do you calculate the p value? P values are usually automatically calculated by your statistical program (R, SPSS, etc.). You can also find tables for estimating the p value…
What is a null hypothesis? All statistical tests have a null hypothesis. For most tests, the null hypothesis is that there is no relationship between your variables…
Similarities and differences between null and alternative hypotheses Null and alternative hypotheses are similar in some ways: They’re both answers to the research question. They…
How to write null and alternative hypotheses To help you write your hypotheses, you can use the template sentences below. If you know which statistical…
The exact procedure for performing a Pearson’s chi-square test depends on which test you’re using, but it generally follows these steps: Create a table of…
There are two types of Pearson’s chi-square tests, but they both test whether the observed frequency distribution of a categorical variable is significantly different from its expected…
Skewness and kurtosis are both important measures of a distribution’s shape. Skewness measures the asymmetry of a distribution. Kurtosis measures the heaviness of a distribution’s tails relative to a normal distribution.…
What is a leptokurtic distribution? A leptokurtic distribution is fat-tailed, meaning that there are a lot of outliers. Leptokurtic distributions are more kurtotic than a normal distribution.…