general Flashcards
why use stats (2)
- tells us how likely our results are to be true
- tells us how wrong our results may be
the sample
the things/people we observe/experiment on
population
where the sample have been taken from, spread across time and space)
what do we use the sample to do
draw inferences about the population
chance is..
responsible for giving the wrong answer
e.g.tossing a coin- if i toss a coin 10 times and get 8 heads, this does not mean that the coin is unfair
why do we use null hypothesis instead of our hypothesis
proving something is true is v hard, easier to prove something is not true
stages of hypothesis testing 3
1) formulate a hypothesis
2) formulate a null hypothesis
3) calc the chance that you might see your data if the null hypothesis were true- p values
what is a p-value
the probability that you might see something as extreme, or more extreme, as that you see in your date under the null hypothesis
what is the normal p value threshold
0.05 -anything below this is seen to be significant and the null hypothesis can be rejected
more modern p-value approach
- 1= weak evidence
- 05= moderate evidence
- 01=strong
- 001= very strong
two types of data
numerical and categorical
two types of numerical data
continuous or count
continous data
can in theory take any value e.g. blood pressure
count data
only integer values and a count of discreet things e.g. number of children
two types of categorical data
nominal and ordinal
