Loading in 5 sec....

Chapter 4: Numeric Ways of Describing DataPowerPoint Presentation

Chapter 4: Numeric Ways of Describing Data

- 69 Views
- Uploaded on

Download Presentation
## PowerPoint Slideshow about ' Chapter 4: Numeric Ways of Describing Data' - xerxes

**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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

### Chapter 4:Numeric Ways of Describing Data

Measures of Center

- Mean
- Formula
- Substitution
- Answer
- Calculator
- Symbols

- Median
- Even, odd sample size

- Using mean vs. median
- Mean for symmetric samples
- Median for skewed samples

Trimmed Mean

- 10% trimmed mean ignores the top 10% and lowest 10% of observations
- Order of resistance to outliers:
- Least resistant:
- Moderately resistant:
- Most resistant:

Mean

Trimmed mean

Median

Proportion

- Symbols
- Proportion is always between 0 and 1

Measures of Spread

- Variance, standard deviation
- Symbols
- Formulas
- Substitution
- Calculator
- Units

Boxplots

- Construction
- 5 number summary: Q1, Q3, median, minimum, maximum
- Outliers: <Q1 – 1.5IQR, >Q3 + 1.5IQR

- Interpretation / Comparing
- Center – median
- Shape – cannot tell from boxplot
- Spread – compare whiskers, upper/lower half of box
- When comparing:
- Look for overlap
- Compare whiskers / boxes – which distribution has more variability?

Boxplot Example

Empirical Rule

- Used for approximately normal distributions
- If a histogram can be well approximated by a normal curve, then:
- Approximately 68% of the observations are within 1 s.d. of the mean
- 95% 2 s.d.
- 99.7% 3 s.d.

Percentile

- Tells proportion/percent of observations at or below that value
- If you score at the 83rd percentile on the ACT, then you scored the same as or better than 83% of students
- If mean is 64 and s.d. is 2, find the score you would need to be at the 90th percentile:

Download Presentation

Connecting to Server..