chapter 4

a casual relationship is where

there is a reason why something happens

example of a casual relationship is

as the age of something increases its value decreases

with lines of best fit, if you have to plot it through the mean point, it means

find the mean of x and the mean of y and plot that point

interpolation is

within the data and therefore is reliable

extrapolation is

outside the data set and is therefore less reliable than interpolation

line of best fit is also known as

the regression line

equation of a line is

y=mx+c

gradient means that

every time that x increases by 1 the y increases/decreases by m

the y intercept is

the initial thing as it is where x is zero

spearman’s rank tests

how strong or weak the correlation between two things are

the equation for spearmans rank is

\

in spearman’s, a perfect positive or negative correlation is

1 or -1

in spearmans, a strong positive or negative correlation is

0\.8 or above, -0.8 or below

in spearman’s a weak positive or negative correlation is

0\.4 or above, -0.4 or below

in spearman’s you have to rank both x and y

the same way

spearman’s rank is represented as

rs

spearman’s rank is designed for

non-linear correlation

what is more suitable for linear correlation

pearsons product moment correlation