Inferential statistics

• Define Inferential statictics

  -Allows us to say whether any difference/relationship is significant
• How do inferential statistics improve a psychological study

  -Allows the researcher to conclude whether the results of a study are significant or due to chance
• What is another way they improve a psych study

  -The researcher is able to determine which hypothesis should be accepted or rejected
• What is another way they improve a psych study

  -Increases the scientific credibility of a study as it provides a more objective result
• What 3 elements do we need to find a critical value

  -Level of significance

  -one/two tailed test

  -number of ppts
• the usual p value used in psych is

  -0.05

  -we have a 95% confidence level that the IV affects the DV and there is only a 5% probability that the results are due to chance
• a directional hyp requires the use of

  -a 1 tailed test
• a non directional hyp requires the use of a

  -two tailed test
• to answer the question you need to

  -find the number of ppts

  -see if the hyp is non direct or directional to determine what type of test to use

  -level of significance

  -find the critical value
• you would then compare this critical value with the

  -calculated value statement to see if result is significant or not
• Outline a model statement of results

  - The result is significant. the calculated value of (blah) is more than the critical value (blah) for a one tailed test where p/<0.05 and df=18

  -therefore we accept the alternative hyp and reject the null hyp

  -reverse for non significant
• In order to select an appropriate statistical test, you need to know the following things:

  -Test of relationship/difference.

  -Experimental design ​

  -Levels of measurement
• what is nominal data

  -data that can be put into specific categories e.g., attachment types
• what is ordinal data

  -Data is ranked

  -difference between each interval is not the same

  -e.g rating scale
• what is interval data

  -data is measured in units of equal interval
• TABLE FOR TEST

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• Outline a model answer of how you would explain your choice


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• Why would a psychologist use a 5% level of significance rather than 1%

  -5% significance is the conventional level of probablity employed by psychologists

  -not a sensitive topic being studied nor one which may affect individuals health as in critical trials