Inferential Statistics

Question 1

Inferential statistics

Answer 1

• Refers to the statistical tests which tell psychologists whether the differences/ relationships found are statistically significant or not
• To be able to tell which hypothesis is met, psychologist must carry out statistical tests to find out if their responses are significant
• Significant Results= ALTERNATIVE HYPOTHESIS ACCEPTED
• Insignificant Results= NULL HYPOTHESIS ACCEPTED

Question 2

Probability Values

Answer 2

• These are significance levels
• **5%(0.05) = 95% confident ** of accuracy (common)
• 1% (0.01) = 99% confident of accuracy (used in life/death situations)

Question 3

Types of Statistical tests

Answer 3

1. Sign test
2. Unrelated t-test
3. Related t-test
4. Man Whitney-U
5. Willcoxon
6. Spearman’s Rho
7. Pearsons R’
8. Chi-squared test
   * The type of test is determined by: method, design, and level of data

Question 4

Types of values

Answer 4

1. Calculated observed value- the result of the statistical test once calculated
2. Critical Value- Found in a table consiting of: probability level, number of participants and whether the hypothesis is one-tailed or two-tailed

Question 5

Sign Test

Answer 5

• Difference
• Repeated measures
• Nominal (categorical) data
• Calculated observed value ≤ critical value

Question 6

Steps for a sign test:

Answer 6

1. Subtract condition 2 from condition 1 and record the sign of the result (+/-)
2. Remove any = from the results and add up the number of pluses and the number of minuses
3. The sum of the lower number of signs (S) is the calculated observed value
4. Then use formula to work out the sign test

Question 7

Mann-Whitney U

Answer 7

• Difference
• Independent measures
• Ordinal data
• Calculated observed value ≤ critical value

Question 8

Wilcoxon

Answer 8

• Difference
• Repeated measures design
• Ordinal Data
• Calculated observed value ≤ critical value

Question 9

Unrelated t-test

Answer 9

• Difference
• Independent measures design
• Interval data
• Calculated observed value ≥ critical value

Question 10

Related t-test

Answer 10

• Difference
• Repeated measures
• Interval Data
• Calculated observed value ≥ critical value

Question 11

Spearman’s Rho

Answer 11

• Correlation
• Ordinal Data
• Calculated observed value ≥ critical value

Question 12

Pearson’s R

Answer 12

• Correlation
• Ordinal Data
• Calculated observed value ≥ critical value

Question 13

Chi-squared test

Answer 13

• Difference
• Independent measures
• Nominal Data
• Calculated observed value ≥ critical value

Question 14

Type 1 error

Answer 14

• Psychologist wrongly accepts the alternative hypothesis

Question 15

Type 2 error

Answer 15

• Psychologist wrongly accepts the null hypothesis