# Course Updates for AP®/College Statistics in July 2021

We are excited to share that we've made significant enhancements to our **AP®/College Statistics** course. One consequence of adding this new content is that it may impact learners’ Mastery percentages.

When we add new content and remove old content, Mastery percentages often change because the **number of available skills changes**. For example, if you mastered 90 out of 100 skills in a course, and we added 10 new skills, your mastery skill count would then be 90 out of 110. This change would change your Mastery percentage from 90% to 82%.

With this specific course update, we expect that Mastery percentages will change by a maximum of **10%**. Most people will see a much smaller Mastery percentage change.

You can see exactly what content items we’ve added and removed below. Happy learning!

**Content Added**

*Articles*

*Exercises*

Develop probability distributions: Theoretical probabilities |

*Videos*

Theoretical probability distribution example: multiplication |

**Content Removed**

*Articles*

Observational studies and experiments |

Positive and negative associations in scatterplots |

*Exercises*

Calculating the median |

Creating dot plots |

Properties of density curves |

Calculating the mean |

Creating box plots |

Area under density curves |

Independent probability |

Probabilities of compound events |

Dependent probability |

Probability in density curves |

Sample size and margin of error in a confidence interval for a mean |

*Videos*

Worked example: Creating a box plot (odd number of data points) |

Worked example finding area under density curves |

Types of statistical studies |

Mean, median, & mode example |

Worked example: Creating a box plot (even number of data points) |

Density curve worked example |

Worked example identifying experiment |

Can causality be established from this study? |

Free-throw probability |

Three-pointer vs free-throw probability |

Sample size for a given margin of error for a mean |