AtlasSession 2L5: Introduction to Numerical Concepts in Researchp.35–46
Types of distribution
Fig. 1
Pore diameter (µm) of a freeze-dried collagen–GAG scaffold by micro-CT
Fig. 1. A bell-shaped pile of 400 pores (pore diameter), highest in the middle at 120 µm and thinning out on both sides; one step of spread is 15 µm. 3 steps either side, 75 to 165 µm, is shaded: more than 99 in 100 pores fall inside. The marked pore, 141 µm, is 1.4 steps above the middle; about 92 in 100 pores are smaller. About 91 in 100 pores are 100 µm or more.
- This pore
- 141 µm
- Steps from the middle
- 1.4 steps above
- Smaller pores
- about 92 in 100
- Pores of 100 µm or more
- about 91 in 100
Distribution Lab · First look
Level 1 · First look · Lecture 5 · p.35–46
Recognise the bell shape and use 'steps of spread' from the middle to say how common a value is.
Apply the 68–95–99.7 rule and z-scores to normal data, and recognise when the t, binomial or Poisson distribution fits instead.
Bell shape (the step you are on)
Adult heights pile up in the middle and thin out at both ends; scaffold pore sizes do the same.
Like adult heights, the pore sizes pile up in the middle, around 120 µm, and thin out at both ends.