Year 1 Chapter 2: Measures Of Location And Spread Flashcards
What is the mode or modal class?
The value or class that occurs most often.
What is the median?
The middle value when the data values are put in order.
What is the mean?
An average of data calculated by the sum of the data / the quantity of the data.
How is mean calculated in a frequency table?
x̄ = Σxf / Σf
How do you find the lower quartile for discrete data?
Divide n by 4.
If this is a whole number, the lower quartile is halfway between this data point and the one above. If it is not a whole number, round up and pick this data point.
How do you find the upper quartile for discrete data?
Divide 3n by 4.
If this is a whole number, the lower quartile is halfway between this data point and the one above. If it is not a whole number, round up and pick this data point.
What is the range?
The difference between the largest and smallest values in the data set.
What is the interquartile range?
The difference between the upper quartile and the lower quartile (Q3 - Q1).
What is the interpercentile range?
The difference between the values for two given percentiles.
What the equation for variance?
(Σx^2 / n) - (Σx / n)^2
What is the equation for standard deviation?
The square root of the variance.
How does the equation for variance change for grouped data?
(Σfx^2 / Σf) - (Σfx / Σf)^2
Where “f” is the frequency for each group and “Σf” is the total frequency.
What is the equation for coded data?
y = (x - a) / b
What is the equation for the mean of coded data?
ȳ = (x̄ - a) / b
What is the equation for standard deviation of coded data?
σy = σx / b
Where “σx” is the standard deviation of the original data.
