maths

Question 1

Spearman’s rank correlation coefficient

Answer 1

see if there is a relationship between 2 numbers

Question 2

what does a positive spearmans mean?

Answer 2

positive correlation

one variable increases, so does the other

closer to 1 = stronger

Question 3

what does a negative spearmans mean?

Answer 3

negative correlation

one variable increases, other decreases

closer to -1 = stronger

Question 4

significance level

Answer 4

must be lower that 0.05
(5% likelihood due to chance)

smaller = less likely due to chance

Question 5

how to calculate degrees of freedom

Answer 5

spearmans = N-2

chi2 = N-1

(N = number of values)

Question 6

chi squared test

Answer 6

shows whether 2 variables are linked

create hypothesis and null hypothesis

do the equation for each location
add the results together = x2

Question 7

significance of chi squared result

Answer 7

compare value to critical value
at 0.05 significance level

x2 < critical = no significant difference
- accept null

significant if x2 > critical
- reject null

doesn’t prove link - correlation doesn’t mean causation

Question 8

IQR

Answer 8

range of values in middle 50%

shows spread of data around median
big = spread out

Question 9

standard deviation

Answer 9

spread of data around mean
big = large spread

+ not skewed by anomalies, unlike range, more reliable

Question 10

measures of central tendency

Answer 10

mean
+considers all data set
-skewed by anomalies

median
+not skewed
-doesn’t consider all data

mode
+not skewed
- biomodal

Question 11

analysing usefulness

Answer 11

needs something to compare it to
= more effective and useful

how skewed it is

how dispersed it is = less constant