This particular cheat sheet is made for my specific Statistics and Probability course. Of course, this is for a mathematics course, so if you are in this class or equivalent, there will be some crossovers. School: Immaculate Heart High School (Los Angeles)
|
Individuals
|
The person or thing described in the data set
|
|
Variables
|
Any attribute for the individuals that can vary
there are two types of variables |
|
Categorical Variable
|
Has a label (favorite color)
|
|
Quantitative Variable
|
Numerical Value and makes sense to find an average (age)
|
|
Frequency table
|
Shows the count of each data point (Blue: 10)
|
|
Relative Frequency table
|
Shows the percentage of each data point.
|
|
Percentage Formula
|
(Part/Whole)x100
|
|
Dot Plots
|
Each dot reprecents one data point (don't skip values that don't have data points
|
|
Skewed Left
|
The tail is on the left (more data is on the right)
|
|
Skewed Right
|
The tail is on the right (more data is on the left)
|
|
Symmetrical
|
The data is split evenly (if you folded it, it would be similar)
|
|
Shape
|
Skewed left/right or symmetric
|
|
Center
|
The typical value in the data set
|
|
Variability
|
How spread out the data is (Variability from __ to __)
|
|
Outliers
|
Values significantly far from the others
|
|
In context
|
Always connect the description to the actual scenario or context of the data
|
|
Described in context
|
The dot plot represents the number of books read last summer. The data is skewed to the right. The center is around around 1-2 books read last summer. The number of books read varies from 0 to 9 books. There is an outlier of 9 books.
|
|
Stemplots
|
Stem and leaf plots organize quantitative data using the digits of the values
|
|
Leaf
|
The last number/digit of the data point
|
|
Stem
|
the other numbers before the last number/digit
|
|
Split Stemplot
|
when each stem has too many data point the stems can be split in two: leaves 0-4 and leaves 5-9
|
|
Info for stemplots
|
- Don't skip stems even if they don't have any leaves!
- Always include a KEY!! |
|
Back-to-Back Stemplot
|
To compare two groups of data you can create a stemplot with leaves on either side. The left represents one group of data and the other side represents the other group
|
|
Standard Deviation (Sx)
|
The average distance from the mean
|
|
Formula: Sx
|
For the sake of your sanity PLEASE use your calculator
|
|
Interquartile Range (IQR)
|
The range of the middle 50% of the data
|
|
Formula for IQR
|
IQR=Q3-Q1
|
|
Bar Charts
|
each bar represents one category and the frequency or relative frequency (Helps compare data side by side)
|
|
Pie Chart
|
the circle represents the whole data set and each wedge represents the relative frequency of a category. Represents data as a part of a whole
|
|
Deceptive graphs
|
Some representation of data are created to manipulate the perception of the data (Always check the scales on a chart and beware of pictographs)
|
|
Step 1
|
Divide your data into equal intervals
|
|
Step 2
|
Create a frequency table for each interval
|
|
Step 3
|
Label the axis. Label the horizontal axis with the intervals
|
|
Step 4
|
Draw the bars for each interval. (no gaps)
|
|
Notes on Histograms
|
The interval contains the first value but not the last
|
|
Relative Frequency histogram
|
- Use the same steps but with a relative frequency table
- When made correctly, all the bars in a histogram should add up to 100% or 1 |
|
Shape
|
Skewed left/right or symmetric
|
|
Center
|
The typical interval in the data set
|
|
Variability
|
How spread out the data is
|
|
Outliers
|
intervals significantly far from the others
|
|
Mean
|
The average value of a data set
|
|
Median
|
The value in the middle of a data set
|
|
Symmetric
|
Mean ≈ Median
- use the mean for center |
|
Skewed Right
|
Mean > Median
- use the median for center |
|
Skewed Left
|
Mean < Median
- use the median for center |
|
Notes on Mean vs. Median
|
If there are outliers, use median for center since median is resistant to outliers. Mean is not resistant to outliers
|
|
Mode
|
The number that appears the most
|
|
Range
|
The difference between the highest and lowest data values
|
|
Quartiles
|
Dividing a data set into four intervals
|
|
First (Lower) Quartile
|
The middle of the lowerr half of the data set. The first quarter
|
|
Second Quartile (Median)
|
Middle Value. The second Quarter of half
|
|
Third (Upper) Quartile
|
Middle of the upper half of the data set. The third quarter
|
|
Boxplots
|
displays data using Min, Max, Q1, Q3, median, and outlier values
|
|
Step 1
|
Create a numberline from the variability of the data
|
|
Step 2
|
Make the Q1, Median, and Q3. draw a box between Q1 and Q3 with a line through the median
|
|
Step 3
|
Mark the Min and Max (excluding the outlier values) and connect them to the box with a line
|
|
Step 4
|
Add * to mark the high and low outliers
|
No comments yet.
Cheatography n. The art of mapping complex subjects into clear, instantly navigable reference guides.
