Research methods 5: Probability and Significance Flashcards
What is an aim?
A general statement about the purpose of the experiment/investigation
What is a hypothesis?
A precise testable statement about what is expected to happen in the study- IV and DV need to be included operationalised
What is an experimental hypothesis?
A predict of what change will take place in the dependant variable when the independent variable is manipulated
What is a null hypothesis?
A hypothesis that there is no significant difference between populations
If the results of the study are significant we…
Accept the experimental hypothesis and reject the null hypothesis
If the results of the study are not significant we…
Accept the null hypothesis and reject the experimental hypothesis
What is a one tailed hypothesis?
A hypothesis that specifies a direction
What is a two tailed hypothesis?
A hypothesis that specifies that significant results will occur, regardless of direction
What is probability?
The likelihood that the results are due to chance or not
How is probability represented in data form?
As P=……
In order for the results to be significant in psychology the results need to be less than…
p = 0.05 (P<0.05)
How likely are results to be due to chance when the results are significant at the P < 0.05 level?
5 percent
What is the purpose of sign tests?
To determine whether something is significant and whether our results can be generalised.
The criteria for using a sign test are:
-Looking for a difference
-Use a repeated measures design
-Data needs to be nominal data
How do you find the S value?
Identify the least frequently occuring sign, so the smallest value.
What do you do once you found the value of S?
Compare the number to another number called the critical value, found on the table provided
What 4 values are needed to find the critical value?
-The significance value you are using (typically 0.05)
-Number of participants in the study (called N)
-Whether the hypothesis is directional or non-directional
-You need to read the rules at the bottom of the table
If S = 1 and the Critical value = 7, what would the results be
We would say that the results are significant, because the critical value is more than the calculated value
When reporting a sign test what format is used?
Since the calculated S value of _ is less than the critical table of , when N =, for a __=tailed, the results are significant/non significant at the P<0._ level. This means that we can accept the experimental/null hypothesis and the null/experimental hypothesis can be rejected. It was found that…
What is a type 1 error?
Where a psychologist incorrectly accepts the experimental hypothesis and rejects the null hypothesis, when they should not as the result was due to chance.
What is a type 2 error?
Where a psychologist incorrectly rejects the experimental hypothesis and accepts the null hypothesis when they should not as the results weren’t due to chance.
What are type 1 and type 2 errors known as?
Type 1- False positive
Type 2- False negative
What are the three significance levels?
-0.01 Stringent
-0.05 Balance
-0.10 Lenient
What does a lenient significant level mean?
-It would be too lenient and result in many researchers making a type 1 error, less likely to make a type 2
What does a stringent significance level mean?
It doesn’t leave much room for error, so psychologists would be more likely to make a type 2 error, less likely to make a type 1
Why do we use 0.05 level of significance?
It’s the common significance level in psychology because it balances ths out and minimises the chances of making type 1 and type 2 errors.
