inferential statistics Flashcards
what is a one-tailed test
directional hypothesis
what is a two-tailed test
non-directional hypothesis
how to calculate the sign test
- identify your categories
- calculate the number of people in each category
- assign the category where there is no difference a 0 sign. These participants are removed from the rest of the test
- Assign one of the other 2 categories a + sign and a - sign
- out of the + and - categories, identify the category with the smallest number. This is S
Conclusion for whether results are significant
The calculated value of ______ is greater than/smaller than/equal to the critical value of _______ (p<________, _____ - tailed test, N =________). This means that the result is/is not significant. This means that we can accept/reject the null hypothesis that ________________________________. [If your result is significant, you then add] This means that we can accept the alternative hypothesis that _________________________________________________________. However, because the significance level was __________, there is still a _______________ probability that the results would have occurred even if _____________________.
what is the aim of statistical testing
to determine the likelihood (probability) that the effect/difference/relationship/association is due to chance
what does p<0.05 mean
there is a less than 5% probability that the difference/effect/relationship/association that has been found is due to chance
benefits of statistical testing
- increases the scientific credibility and objectivity of research
- allows the researcher to determine whether the null hypothesis should be accepted or rejected
what is a significance level
the point at which the researcher can claim to have discovered a significant difference or correlation within the data.
Or the point at which the researcher can reject the null hypothesis and accept the alternative hypothesis
why do psychologists sometimes use stringent/lower significance levels?
In studies where there may be a human cost, or one-off studies that for practical reasons could not be repeated in the future
what decisions are needed to determine which statistical test is used
- level of measurement
- is the study a test of difference, correlation or association?
- experimental design
what is the difference between correlations and associations
- correlations are relationships where both variables are ordinal or interval data
- associations are relationships where both variables are nominal
what is a related design
when matched pairs or repeated measures has been used
test of an association
what is an unrelated design
when an independent groups design has been used
test of a correlation
decision table rhyme
Can Simon Cowell Make Winners Sing Under Real Pressure
How to check for a type 1 error
-keep the tailed test and the N/df the same
- change the significance level to the smallest one you can
- check if the calculated value is still significant or not
- if it is, a type 1 error has not been made. If it’s not, a type 1 error has likely been made
what is a type 1 error
when the null hypothesis is rejected but should have been accepted because it is ‘true’
- occurs when the significance level is too lenient (p<0.10)
- the likelihood of making a type 1 error is the same as the significance level
what is a type 2 error
- when the null hypothesis is accepted but should have been rejected because the alternative hypothesis is ‘true’
- occurs when the significance level is too stringent (p<0.01)
checking for a type 1 error conclusion
- Currently, we are approximately ______% confident in our rejection of the null hypothesis because a ________ significance level has been used. This means that there is still a less than _____% probability of rejecting the null hypothesis when it is true and making a type 1 error. To check this, a more stringent significance level of ______ should be used which reduces the probability of a type 1 error having been made to less than ____%, making us more confident that a type 1 error hasn’t been made. When this significance level is used, the calculated value of ____ is greater than/less than/equal to the critical value of _____ (p<________, ____-tailed test, N/df = _____). This means that the result is still significant/is no longer significant. This suggests that a type 1 error has been made and so the null hypothesis should be accepted/this suggests that a type 1 error is unlikely to have been made as there is only a less than ___% probability of this and so we can be more confident in rejecting the null hypothesis.
why is the significance level of 0.05 used
it is a balance between making a type 1 error and a type 2 error
