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AP Statistics: Chapter 1
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Terms in this set (47)
Statistics
the science of collecting, organizing, and interpreting numerical data
Individuals
Objects described by a set of data
Variable
Any characteristic of an individual (can be measured, recorded)
Objects
People, animals, things
Categorical variable
Records which of several groups an individual belongs to
Quantitative variable
Take numeric values for future calculations or interpretations
What kind of variable is gender?
Categorical
What kind of variable is race?
Categorical
What kind of variable is heart beats/minute?
Quantitative
Distribution
Tells what values a variable can be and how often it takes on these values (frequency)
Stemplots
Give a picture of a distribution, while including the actual data values
Splitting stems
If all data falls within a small number of stems you can double the stems and place 0-4 on the first stem, and 5-9 on the second stem
Examining characteristics of a distribution
Center, shape, and spread
In a distribution, identify any...
Outliers
Modes
Any major peak
Unimodal
A distribution with only one major peak
Bimodal
A distribution with two peaks
Symetric distributions
the right hand side and left hand side are approximate mirror images of each other
Skewed right
Right tail is longer
Mean is greater than median
Skewed right
Skewed left
Left tail is longer
Mean is less than median
Skewed left
Where is the mean in a distribution?
In the skew
Histogram
A graph of distribution with one quantitative variable
Center
Mean, median
Shape
Symetric or skew
Spread
Range
Timeplots
Plots each observation against the time at which it was measured. Always mark the time scale on the horizontal axis and always the variable being measured on the vertical axis. Individual values may be connected. Trends should be noticed
Mean equation
Non-resistant to extreme values, and an outliers will pull it in one direction
Mean
Middle number when all values are in order, and resistant to extreme values
Median
Q1
Median of the lower half of data
Q3
Median of the upper half of data
IQR
Q3-Q1
Outlier
All data outside an acceptable range
Boxplot
A graph based on the 5 number summary (min, max, Q1, Q3, M)
Variance
s², of a set of observations is the average of the squares of the deviations of the observations from their mean
Variance formula
Standard deviation
s, is the square root of the variance
Standard deviation formula
The sum of the deviations of the observations from the mean is
0
Degree of freedom
n-1, refers to how many numbers must be known to before all n numbers are known
The first n-1 observation are...
Free to be any numbers
The final value is...
Is not free of a statistic
"s" measures...
The spread about the mean
When does S=0?
Only when there is no spread (if all values are the same)
"s" is non-resistant/resistant?
Non-resistant
;