Understanding Inf Stats Flashcards
Distribution, Probability, Significance
What are inferential statistics?
They allow you to infer if your hypothesis is correct (is it actually significant?) and assess whether data can be generalised to the target population
Distribution
What is distribution?
How spread out the data is when plotted on a frequency graph
Distribution
What does a normally distributed curve look like?
Symmetrical curve and no clear “tail”
https://vt-s3-files.s3.amazonaws.com/uploads/problem_question_image/image/23754/SATNorm.png
Distribution
What does a skewed positive distribution curve look like?
The “tail” is longer where majority of scores are larger
Tail points towards positive numbers (if on a 4 quadrant graph)
https://th.bing.com/th/id/OIP.H_hIo2hNlk1i5HtapGVhRAHaI4?rs=1&pid=ImgDetMain
Distribution
What happens to measures of central tendancy on a positive skew?
Mean, mode, median
They decrease in value
Distribution
What does a skewed negative distribution look like?
The “tail” is longer where majority of scores are smaller
https://th.bing.com/th/id/OIP.PbBsKbFJ5rp4r2icrr6GEQHaIs?rs=1&pid=ImgDetMain
Distribution
What happens to the measures of central tendancies on a negative skew?
Mean, mode, median
They’ll increase in value
Probability
What is probability?
A numerical value that represents the likelihood of some event happening
Probability
What word could be used to describe probability?
Significance- is it significant or not?
Probability
What scale is probability measured on?
Scale from 0-1
Probability
What does 0 as a value mean in terms of probability?
It will never happen
E.g. probability of rolling a 7 on a six sided dice= 0
Probability
What does 1 as a value mean in terms of probability?
It will definitely happen
E.g. probability that the sun will rise= 1
Error
What is a type 1 error?
False positive- Accept alternate hypothesis when in fact the results were due to chance
No significant difference
Error
What is a type 2 error?
False Negative- Accepting null hypothesis when the alternative hypthesis was correct
There is a significant difference
