Chapter 2 Flashcards
What is a measure of location?
A single value which describes a position in a data set.
What is a measure of central tendency?
A single value that describes the centre of the data.
How do you calculate the mean?
x̄ = Σx/n
mean = the sum of all numbers / the amount of numbers
What is the mode?
The value with the highest frequency.
How do you calculate the median?
Total of numbers divided by 2
When is the mean used?
When the total quantity is of interest, or if it is necessary to take all values into account.
How do you calculate the mean when given data values in a frequency table?
x̄ = Σxf/Σf
The sum of the products of the data values and their frequencies / the sum of the frequencies
What is the formula to work out quartiles?
(Q1/2/3 - lower end of class width) / (class width range) = (nth value - lower cf) / (cf range)
What is the formula to work out percentiles?
(P - lower end of class width) / (class width range) = (nth value - lower cf) / (cf range)
What is the interquartile range?
IQR = Q3 - Q1
How do you work out the variance?
mean of the squares - square of the mean
(x̄²) - (x̄)² = σ²
How do you work out the standard deviation?
square root of mean of the squares - square of the mean
σ = √(x̄²) - (x̄)²
What does coding help with?
Makes the numbers in a data set easier to work with.
What is the coded data formula?
y = x - a / b
What is the mean of the coded data formula?
ȳ =x̄ - a / b
