Data Flashcards
What is x bar and how is it calculated
It is the mean of the data
Sum of x over n
Or sum if f over f in grouped data
In listed data how do you calculate the position of the 3 quartiles
Lower - take number of data and divide by 4
Median - take data and divide by 2
Upper - multiply n by 3 and divide by 4
What do you do if you get a decimal or a whole number when calculating quartile position for listed data
Decimal - round up
Whole - find midpoint with next number
How do you calculate the quartile position in grouped data
Same as listed data n/4 etc
How do you find percentiles in grouped data
Multiple decimal of percentage by n
Ie 57th is 0.57 x n
How do you find deciles in grouped data
D3 is 0.3 multiplied by n
Based on how much percent
How do you do linear interpolation
Find group it lies in using cumulative frequency
Calculate fraction you need to go along multiplied by class width
What is the interquartile range, what is an advantage of it
Q3 take away Q1
Ignores extreme values
How do you calculate interpercentile range
10th to 90th is
P90 - P10
What is relation between variance and standard deviation
Variance is the standard deviation squared
How do you draw a box plot from a cumulative frequency graph
Draw the 3 quartiles and the top and bottom value
Min Q1 Q2 Q3 and maximum
And then outliers on end
How do you calculate an outlier
Q1 - 1.5 X IQR
Q3 + 1.5 X IQR
When do you use histograms
For continuous diagrams
How do you calculate frequency density
Frequency / class width
If you are asked to compare 2 histograms, what 2 comparisons do you make
1 measure of location ( quartiles etc)
1 measure of spread
Context
