Stats Flashcards
Mode
Number that appears the most
Mean
Average. Determined by: sum of the terms / number of terms
Median
Middle number in ordered set. Determined by n+1/2.
(n is sample size/number of digits)
n
sample size/number of digits
Quartiles
divides data set into quarters. data must be ordered.
Q2 =
median
interquartile range
the difference between Q3 and Q1
range
Simplest measure of spread. Cannot be used for grouped frequency table. Affected greatly by outliers
Outlier
an extreme value in the data set: significantly larger/smaller
how to identify an outlier?
If value < Q1 - (1.5 x IQR)
or value > Q3 + (1.5 x IQR)
Lower quartile formula?
n+1 / 4
Upper quartile formula?
3(n+1) / 4
What is Σ?
Sigma. Means ‘sum of’
5 Number summary consists of?
- min value
- Q1
- Q2 / Median
- Q3
- max value
cumulative frequency
running total
An ogive should be in an _____ shape.
S
what do ogives illustrate?
cumulative frequency
what is standard deviation?
- how far typical data values deviate from the average/mean
- the larger the distance is compared to the st dev, the more extreme the observation
- σ
what is variance?
- the square of the standard deviation
- σ²
what does it mean if data is negatively / left skewed?
mean < median
what does it mean if data is positively / right skewed?
mean > median
How do you graphically represent a five number summary?
box and whiskers plot
describe a box and whiskers plot
end of left whisker: min value
left of box: Q1
middle of box: Q2
right of box: Q3
end of right whisker: max value
can help to draw a number line underneath
