Probability And Statistics Flashcards
What is probability (p)?
A numerical measure of likelihood/chance that a certain event will happen
E.g probability of rolling an odd number on a dice is 50percent
What is significance?
A statistical term used to indicate whether research findings are sufficiently strong enough to reject the null hypothesis and accept experimential hypothesis
In psychology the accepted level of significance is usually p less than/= 0.05
What is a type 1 error?
An error which occurs when a researcher rejects a null Hypothesis
E.g man is pregnant
What is a type II error?
An error which occure when a researcher accepts null Hypothesis which was not true
E.g women is pregnant not pregnant
Why are we more likely to make a type 1 error?
If the significance level is too leintent (too high)
E.g 0.1 (10 percent rather than 5 percent)
Why. are we more likely to make a type II error?
If the significance level is too stringent (too low)
E.g 0.01 ( 1 percent than 5 percent )
Why do psychologists favour 5percent significance level?
Best to balance the risk of making Type 1 or Type II error.
What is the difference of alternate and null Hypothesis?
Anull hypothesisis ahypothesisthat says there is no statistical significancebetweenthe two variables. It is usually thehypothesisa researcher or experimenter will try to disprove or discredit. Analternative hypothesisis one that states there is a statistically significant relationshipbetweentwo variables
Alternate providing evidence to support hypithesis and falsify the other hypothesis
What tests used to test for a difference?
- Mann whitney
- Wilicoxon
- Unrelated t- test
- Related t- test
What tests used to test for correlation?
- Spearman’s Rho
- Pearsons R
What test used for association?
Chi- squared test
Also used to test for difference - both aspects
What are the three factors used to devise which test used under certain circumstances?
- Whether you are looking for a difference or a correlation
- in case of difference - what experimental design used?
- what level of measurement of data is - e.g nominal ,ordinal , interval
Recap experimental design:
- Repeated measures : same participants do condition A and B
- Independent measures : Participants randomly allocated to condition A or B
- Matched Pairs: Grouos matched then randomly allocated to condition A or B
Three levels of measurement- QUANTATIVE
- Nominal
- Ordinal
- Interval
What is nominal data?
When data is in the form of categories, data and can only appear in one category
Most basic level of measurement
