2025-09-16

Agenda

  • This presentation will in broad strokes cover P Values.
  • We will look at some examples of graphs in both two dimensions and three dimensions that have a normal distribution.
  • We will also look at the formula for how to calculate standard deviation and the general formula for determining a Z Score.

Need To Known Formulas

Standard Deviation: \(\sigma = \sqrt{\frac{1}{n}\sum_{i=1}^{n}(x_i - \bar{x})^2}\).

  • The above formula above is how we can calculate Standard Deviation given a data set

  • \(x_i\). = Each of the values of Data.

  • \(\bar{x}\). = The mean of \(x_i\).

  • \(n\).= The Number of Data Points

  • Next we will look at a graph in 3d that has a normal standard deviation distribution.

3D mtCars data set

Need To Known Formulas Continued

  • How to determine Z Score: \(z = \frac{x - \mu}{\sigma}\)
  • \(x\) = Observed Value
  • \(\mu\) = Population Mean
  • \(\sigma\) = Population Standard Deviation
  • Z Scores are used in a Z-Test which is used in Hypothesis Testing

Lets examine a Standard Graph

ggplot(mtcars, aes(x = hp, y = mpg, color = factor(cyl))) +
  geom_point(size = 3) +
  labs(title = "Miles per Gallon vs Horsepower",x = "Horsepower (hp)",
    y = "Miles per Gallon (mpg)",color = "Cylinders" ) +theme_minimal()

Determining a P Value

  • After we look at the graph in the previous slide we can compare and evaluate the significant results by using our P value.
  • The standard P Value for studies historically has been \(0.05\)
  • P values are in essence a measure of statistical significance
  • A large P Value would suggest the results are likely due to random chance
  • Our next slide will cover bar plot Comparing Average MPG by number of cylinders in a car
  • What hypothesis would you have about the data in the next slide?

Bar Plot

Conclusion

  • While not a comprehensive look at P-Values, we were able to use some of the tools of ioslides to create visual aids for our presentation.
  • Thank you for engaging with my presentation on P values.