Trade-off between Type I and Type II errors The Type I and Type II error rates influence each other. That’s because the significance level (the…
Error in statistical decision-making Using hypothesis testing, you can make decisions about whether your data support or refute your research predictions with null and alternative hypotheses.…
What does a correlation coefficient tell you? Correlation coefficients summarize data and help you compare results between studies. Summarizing data A correlation coefficient is a descriptive statistic. That…
What is the Pearson correlation coefficient? The Pearson correlation coefficient (r) is the most widely used correlation coefficient and is known by many names: Pearson’s r…
What is right skew (positive skew)? A right-skewed distribution is longer on the right side of its peak than on its left. Right skew is…
Types of descriptive statistics There are 3 main types of descriptive statistics: The distribution concerns the frequency of each value. The central tendency concerns the averages of the values.…
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…