Statistical tests Flashcards
What is the purpose of standard deviation
show frequency of data around a central idea
-use with pie chart
-bar chart
What is the purpose of a Spearman’s rank correlation
shows the strength and nature of correlation between 2 sets of data
What is the purpose of a location quotient
determines spatial distribution in a sub area compared to overall area
What is the purpose of mann-whitney U
shows whether 2 data samples are significantly different from one another
What is the purpose of chi-squared
shows if there is a significant difference between observed & expected values
What is the purpose of t-test
looks at means of 2 sets of data & decides whether theres a significant difference between the 2
How do you work out the mean
add up all data & divide by how many there is
How do you work out the range
largest value - smallest value
How do you work out the mode
order numbers lowest -> highest
-find most common number
How do you work out the median
write the data in order and find the middle number
How do you find the lower and upper quartiles
write data in order
-find median
-middle of one end
-middle of other end
e.g. -
0 2 4 5 7 8 10 12 12 12 13
8 = median (6th value)
4 = lower quartile (3rd value)
12 = upper quartile (9th value)
Name the 5 steps for carrying out standard deviation
-find mean
-for each data point find square of its distance to mean
-sum values
-divide by number of data points
-take square root
What does a null hypothesis mean in spearmans rank
-there is no correlation between the 2 data points
-but if there is a relationship between the 2 data points -> its a hypothesis
Name the 7 steps carried out in the t-test
1 - square individual values of x1 & x2
2 - calculate sums of all x values
