1 / 13

A Day of Classy Review

A Day of Classy Review. Shifting and Scaling. SAT/ACT Max SAT: 1600 (old school) Max ACT: 36 SAT = 40 x ACT + 150. ACT Summary Stats: Lowest = 19 Mean = 27 SD = 3 Q3 = 30 Median = 28 IQR = 6 Find equivalent SAT scores. SAT and ACT. ACT Summary Stats: Lowest = 19 Mean = 27 SD = 3

uri
Télécharger la présentation

A Day of Classy Review

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. A Day of Classy Review

  2. Shifting and Scaling • SAT/ACT • Max SAT: 1600 (old school) • Max ACT: 36 • SAT = 40 x ACT + 150 • ACT Summary Stats: • Lowest = 19 • Mean = 27 • SD = 3 • Q3 = 30 • Median = 28 • IQR = 6 • Find equivalent SAT scores

  3. SAT and ACT • ACT Summary Stats: • Lowest = 19 • Mean = 27 • SD = 3 • Q3 = 30 • Median = 28 • IQR = 6 • SAT = 40 x ACT + 150

  4. NormalCDF • The NormalCDF( function finds the percent of the total area of the distribution that falls between two z-scores. • For example, what would the NormalCDF(-1,1) be? (Hint: 68-95-99.7 rule)

  5. NormalCDF Procedure • First, determine the type of question being asked • Once you’ve determined it is appropriate to use the NormalCDF function, convert given values into z-scores

  6. NormalCDF • Questions: • What percent of the distribution falls between X and Y? • What percent of the distribution is greater than Y? • What percent of the distribution is less than X? • Answers: • NormalCDF(X,Y) • NormalCDF(Y,99) • NormalCDF(-99,X)

  7. invNormal( Going the Other Way • The invNormal( function finds what z-score would cut off that percent of the data • Example: What z-score cuts off the top 10% in a Normal model? The bottom 20%? • The trick here is figuring out what percent (as a decimal) to enter in to the function. • Imagine invNormal calculates the area starting at -99. • So to find the z-score that cuts off the top 10% we want the z-score that includes 90% • invNormal (.9) = 1.28

  8. invNormal( Example • Based on the model N(1152, 84) describing angus steer weights, what are the cut-off values for • A) highest 10% • B) lowest 20% • C) middle 40% • A) invNormal(.9) = 1.28 • B) invNormal(.2) = -.842 • C) invNormal(.3) = -.524 invNormal(.7) = .524 • 1,259lbs • 1,081lbs • 1,108 – 1196lbs

  9. New Topic – Normal Probability Plots • How to decide when the normal model (unimodal and symmetric) is appropriate: • Draw a picture (Histogram) • Draw a picture! (Normal Probability Plot) • A Normal Probability Plot is a plot of Normal Scores (z-scores) on the x-axis vs the units you were measuring on the y-axis (weights, miles per gallon, etc.) • A unimodal and symmetric distribution will create a straight line

  10. What it Looks Like

  11. What it Looks Like

  12. How It Works • A Normal probability plot takes each data value and plots it against the z-score you would expect that point to have if the distribution were perfectly normal • These are best done on a calculator or with some other piece of technology because it can be tricky to find what values to “expect”

  13. Page 136-141 # 3, 5, 12, 17, 28, 30 Homework

More Related