Chapter 3 Representations Of Data - Year 1 Flashcards
What are the 2 methods used to identify outliers?
1.5IQR’S beyond the upper or lower quartile
+or- 2 standard deviations from the mean
How do you draw a box plot with an outlier?
You draw it normally with the range changed to the second value that they give you (or the upper/lower bound that you worked out) BUT ONLY DO 1
You need to put a cross where the outlier was
What can you compare between box plots?
IQR and Median
You don’t need to use numbers
What is important to remember with cumulative frequency graphs?
You always plot at the upper bound
What is important to remember about histograms?
Frequency = the area
Frequency = Class width X Frequency Density
How do you justify the use of a histogram?
Continuous data is being used
What do you need to check with in all histogram questions?
How?
If there is a scalling factor
You add numbers by yourself and calculate the frequency in your diagram
Then compare it to the frequency given
How do you estimate the median value of a histogram?
Interpolation
How do you estimate the mean of a histogram?
Your scaling factor X (the Frequency X The midpoint of bar 1) … of all the bars
All divided by the total frequency
How do you deal with gaps?
Adjust the groups so that they cover the full range (this usually means increasing and decreasing them all by 0.5
If you are told the class width and the frequency as well as the height and width of the bars of 1 of the intervals how do you work out the height and width of the other classes?
For width you do the stated length / class width
Then the class width of the other class X the above reuslt
For height it is the same process but you need to work out the frequency density before and use that.
It is always the stated number divided the actual number
What are the 3 things you need ro remember when you draw a frequency polygon from a histogram?
You plot from the midpoint
If FD=0 you plot at the bottom
Straight lines
