Module 2-2 Flashcards
What are the ways to Summarize Categorical (Qualitative) Data?
Bar Chart
Pie Chart
What are the ways to Summarize Numerical (Quantitative) Data
Dot Plot Stem Plot Histograms Time Plots Box Plots Scatter Plots
What are they ways to describe Summarizations?
Shapes
Center
Spread
What are the types of Shapes 1?
Modes
Symmetry or Skewness
Deviation or outliers
What are the types of Shapes 2?
Uniform - No mode
Unimodal - A single peak
Bimodal - Two peaks
When is a graph symetrical?
When you can draw a vertical line so that the both sides are mirror images
What does a Positively skewed, or skewed to the right graph look like?
A peak more to the left
What does a Negatively skewed, or skewed to the left graph look like?
A peak more to the right
What is Skewness caused by?
Unusual values or deviation from overal pattern
What is the Center?
The value that splits the data in half or a typical range of values at the center of the graph
What are the types of Centers?
Mean, Median, Mode
What is Spread?
The range of values. If they are far apart or close together
What is the most common type of graph?
A Histogram
What is the downside to histograms?
Data values from a stem and leaf plot are retained but not with histograms
How does an outlier affect a mean?
If the set of observation includes an outlier, the mean value will be drawn in the direction of the outlier
What is the mean not resistant to?
Outliers
What do we use instead of mean when there are outliers?
Median
What is the Median?
The value that divides the ordered sample in two sets of the same size
How can the median be found?
By finding the value that is in the middle, if there is an even number take the value of the two numbers in the video
What is the mode?
The value that occurs with the highest frequency in a data set
What does the mode look like on a graph?
Where the distribution is tallest
What are the mean, median and mode in a symetric distribution?
ȳ = M = mode
What is the relationship with the mean, median and mode in a positively skewed distribution?
mean > median > mode
What is the relationship with the mean, median and mode in a negatively skewed distribution?
mean < median < mode
What are the 3 measures of Variability?
Range
Variance and standard deviation
IQR
What is the range?
Range is the simple numerical measure of variability that gives the difference between the largest maximum and the smallest minimum
What does a large range mean?
A greater variability
What is deviation?
The difference of an observation from the mean (y)
When is a deviation positive?
If the observation is greater than the mean
When is the deviation negative?
When the observation is less the the mean
What is the formula for deviation?
(observation-mean)
What does the Set of Deviations describe?
The variability of the data
What is Variance?
The sum of the squared deviations
What is the Standard Deviation?
The square root of the Variance and is denoted by s
What is the most commonly used measure of Variation?
Standard Deviation
When does the standard deviation equal 0?
When there is no spread
When does is the standard deviation greater than 0?
When the observations become more spread out
What is the Standard deviation not resistant to?
Skewness
When is Interquartile range (IQR) used?
When there are outliers
What is used as the center in Standard deviation?
Mode
What is used as the center in IQR?
The Median or Q2
When will the IQR be small?
When the data is clustered around the center
what does a boxplot show?
The center, spread, and symmetry or skewness at the same time
