Statistical Testing and Probability Flashcards
What is statistical testing
It is a method used to see if a hypothesis should be accepted or rejected
Why do we use statistical testing (2 reasons)
.they work out the probability of whether a particular set of data could have imply occurred by chance
.find a difference between 2 soles but we want to know if the difference is big enough for it be be significant
What information do you need to know to determine what statistical test to use
3 D’s:
.level of Data (nominal,ordinal or interval)
.type of Design (related or unrelated)
.test if Difference or correlation
What experimental designs are ‘related’ designs
Repeated measures or matched pairs
What experimental designs are ‘unrelated’ designs
Independent group or single participant
What is the mnemonic for determining which statistical test to use
Simon Cowell Wants More Singers Receiving Unanimous Praise
What does the mnemonic correspond to for the statistical tests
Sign tests, Chi squared, Wilcoxon, Mann whitney, Spearman’s rho, Related T, Unrelated T and Pearsons
When do we use the sign test
When it is a test of difference and related design and when the data is nominal
What is the sign test
It is a calculation used to determine whether a difference is statistically significant
What is the first step for the sign test
Put the pairs of related data into the table (going to be already done for you most times)
What is the second step of the sign test
Subtract the values in the pair and label it with their + if it is a positive number or a - if it is a negative number
What is step 3 of the sign test
Count how many - and + there are and the one which has a lower number is the S value
What is step 4 of the sign test
Compare the calculated value (S) with the critical value
What criteria’s do you need to follow to find the critical value from the critical value table
.One or two tailed hypothesis?
.How many total participants? (Take away those who have no difference)
.What level of probability are you using?
What is a one tailed hypothesis
A directional hypothesis
What is a two tailed hypothesis
non directional hypothesis
What level of probability is always used (unless said otherwise in question)
0.05 (5%)
What do you use when comparing the S and CV and determining whether the hypothesis is significant
The statement below the critical value table
What other 2 probability values may be used by psychologists
0.1 or 0.01
Why is 0.05 the probability level that psychologists work at
Because they need to be 95% sure of their research and so that errors are reduced but also so that the data isn’t too strict that it leads to more type 2 error
What type of error is more likely to be cause because of 0.1 probability level
Type 1
What type of error is more likely to be cause because of 0.01 probability level
Type 2
What is a type 1 error
When the investigator rejects a hypothesis or data but it is actually right (false positive)
What is a type 2 error
When the investigator thinks a hypothesis or data is true but it is actually false (false negative)
What is a null hypothesis
A hypothesis that states that there is no relationship between the 2 variables
Do you have to know how to calculate the other stats test other than sign tests
No
What do you have to know about the other stats tests
Know when to use them and compare critical and calculated value and state if its significant
When do you use wilcoxon
Test of differences, related designs and ordinal data
When do we use Mann Whitney
Test of difference, unrelated design and ordinal data
When do we use spearman’s rho
Correlation and ordinal data
When do we use chi squared
Test of difference, unrelated design and nominal data
When to use Pearsons r
Correlation and interval data
When to use T tests (related and unrelated)
Test of difference, corresponding design and interval data
When is 0.01 probability level used
When the researcher needs to be more confident and eliminate as much chance of uncertainty as possible. Also mainly when there is a human cost such as drug testing, you want to be more careful and be 99.99% sure
