Chapter 3 Flashcards
Measures of Central Location:
Mean (average): weakness is that it can be influenced by outliers
Median: middle of the data set
Mode: most frequently occurring value (could have more than one - multi-modal data sets)
Weighted Mean: adding different weights to each observation (all sum to 1) Ex. grades
Mean (average):
Mean (average): sum of all the values/total number of values
- population with mew
pth percentile:
pth percentile: divides the dataset into two parts - calculate by ascending order ??? N = population size n = sample size
Boxplots:
Boxplots: show us the 5 number summary of the data set, plotted in ascending order, box on Q1 & Q3 with median dotted line, add a whisker to min & max (1.5 IQR), tell us where the outliers are
- min
- 1st, 3rd quartile
- median
- max
Measures of Dispersion:
Measures of Dispersion: gauge the variability of a data set
- Range
- Absolute Mean
Range:
Range = Max - Min
Absolute Mean:
sum of all values/total pop or sample size
MAD = Mean Absolute Deviation
Variance
Sample Variance: divide sum by n-1, we use x-bar
Population Variance: divide by N , we use mew
Standard Deviation:
Standard Deviation: the square root of the variance
Coefficient of Variation:
CV = s/x-bar
Pop CV = sigma/mew
Covariance
shows the direction/linear relationship between two variables (not really the magnitude)
Negative value for covariance:
Negative value for covariance: negative linear relationship
Positive value for covariance:
Positive value for covariance: positive linear relationship
Zero value for covariance:
Zero value for covariance: no linear relationship
Correlation Coefficient
Correlation Coefficient:
- describes the direction & strength of the linear relationship
- always between -1 and 1
