Statistics Flashcards
what is null hypothesis
Its a hypothessi written alongside the alternative/experimental hypothesis
where it states that there is no difference between the variables and any difference is due to chance
RESEARCHERS NEVER WANT TO ACCEPT THE
null hypothesis
what are statistical tests used for
statistical tests are used to determine which hypothesis should be accepted and which should be rejected by using probability
0 =
statistical impossibility
1 =
statistical certainty
what is a level of significance?
that the results are NOT due to chance and so finding’s are significant
The confidence/significance level in psychology is
0.05% P <0.05
this means that there is a 5% or less likelihood that the results are due to chance
OR
A 95% likelihood/confidence that the findings are not due to chance
The null hypothesis rejection means that
results are significant
The null hypothesis acceptation means that
results are insignificant
Explain a type 1 error
When the Null hypothesis has been rejected when it should have been accepted.
This means its been too lenient - Optimistic
(level of significance of 10%)
Explain a Type 2 error
When the Null hypothesis has been accepted when it should have been rejected.
This means its been too Strict - Pessimistic
(level of significance of 1%)
Why do we use a level of significance of 5% in Psychology?
Psychologists favour the 5% level of significance as it best balances the risk of making a Type 1/Type 2 error
How is a statistical test chose the 3 steps
- difference/correlation
2, independent groups/repeated measures/matched pairs design - level of measurement of the data - Nominal, Ordinal or Interval
Nominal data
when you have been counting things and putting them into categories, no ranking as the data is frequencies.
Discrete only appears in one category
Ordinal data
when you have been measuring things and have data that can be ranked in order of size - there is no scale of measurement with equal units.
Lacks precision based on subjective opinions
Interval data
when you have been measuring things on a scale with equal units
The most precise and sophisticated form of data
Sign test requirements
- test of difference
- nominal data
- repeated measures
Statistical analysis test steps SIGN TEST
- convert data into appropriate level of measurement - nominal
- calculate difference between the 2 scores of P’s
- Increase write + / decrease write -
- no increase/decrease write 0/= and exclude these scores from the investigation and the participants
- The number of less frequent sign is the Calculates/Observer value
STEP 2
use the critical value data to gain the critical value for the investigation
STEP 3
critical value should be compared to the observer value and the observer value should be less than or equal to the critical value IF NOT THE NULL HYPOTHESIS SHOULD BE ACCEPTED AS THE RESULTS ARE INSIGNIFICANT
Spearman’s Rho test requirements
used when the hypothesis predicts correlation between 2 co variables
correlation
Ordinal data
equal to/ greater than critical value
Pearson’s R test requirements
f
Chi-Squared requirements
f
Wilcoxon T test requirements
f
Man Whitney U test requirements
f
Unrelated T test requirements
f
Related T test requirements
f
What are the 8 statistical tests
- Sign test
- Spearman’s Rho test
- Pearson’s R test
- Chi-Squared
- Wilcoxon T
- Man Whitney U
- Unrelated T
- Related T
