2.7.8 Inferential Stats

Question 1

which stats test is appropriate for the stroop/imp. investigation

Answer 1

Spearmans correlation coeffeicient (P also signified by Rs)

Question 2

why is Spearmans appropriate for the stroop/imp. investigation

Answer 2

• measures the strength and direction of association between two ranked variables
• The study was looking for a relationship between the co-variables of impulsiveness and stroop performance
• Both scores from the stroop test and impulsivity scale were analysed at an ordinal level

Question 3

what is the purpose of carrying out a stats test

Answer 3

• The purpose of carrying out a stats test is to generate the observed value (calculated value)
  > Once you have OV, you can then check this OV against a critical value

Question 4

what are the 3 factors for your correlation?

Answer 4

1. Level of significance: 0.05
2. Number of participants
3. direction of alternative hypothesis

Question 5

Explain what the 5% level of significance means and why you chose it for your correlation

Answer 5

If the results of the study were found to be significant at the 5% level of significance it means if the study was carried out 100 times, 95% of the time the result would support the directional / non-directional hypothesis (alternative hypothesis)

5% level of significance = minimum acceptable level for deciding if the results are significant
- less likely to make a type 1 or type 2 error

Question 6

what happens if there is less than 5% probability

Answer 6

If there is a less than 5% probability, the results are due to chance

Question 7

what is a type 1 error

Answer 7

when the null hypothesis is rejected when it is in facture
> happens when using 10% level which is too lenient

Question 8

what is a type 2 error

Answer 8

when the null hypothesis is retained when it should have been rejected > happens when we use a stricter level of significance (e.g. 1%)

Question 9

how do you know if the hypothesis is accepted

Answer 9

If the observed value is smaller than the critical value the result is not significant and the null is accepted

Question 10

how do you know if the hypothesis is rejected

Answer 10

If the observed (calculated) value is equal to or greater than the critical value, this means the results of the correlation are significant, so the null hypothesis would be rejected

Question 11

what were the results from your Spearmans test

Answer 11

observed value = 0.365
critical value (Dir. hyp.) = 0.564
critical value (Non-Dir. hyp.) = 0.648

Question 12

what is your statement of significance

Answer 12

As the observed value of 0.365 was smaller and the critical value of 0.648 at the 0.05 level of significance the result is not significant and the null hypothesis is retained

Results show there is a small positive correlation between the co-variables of stroop performance and impulsiveness scores as measured using Barratt impulsiveness scale, however it is not a significant correlation relationship

Therefore there is no significant relationship