Biological psychology Practical Investigation

Worked examples (9)

• 1Identify the co-variables and say why there is no IV (3 marks)
• 2Write a directional alternative hypothesis (3 marks)
• 3Write the matching null hypothesis (2 marks)
• 4Operationalise a self-rating so it can be reproduced (4 marks)
• 5Justify directional rather than non-directional (4 marks)
• 6Justify the sample size from the critical value table (4 marks)
• 7Address the ethics of asking about one's own irritability (5 marks)
• 8Identify the controls and say what each prevents (6 marks)
• 9Spot the flaws in a proposed correlational design (6 marks)

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Worked examples (9)

• 1Identify the sampling technique and the target population (3 marks)
• 2State the level of measurement of each co-variable (3 marks)
• 3Select the inferential test and give all three reasons (4 marks)
• 4Explain why the significance level is set in advance (3 marks)
• 5Work out what the tails decision costs (4 marks)
• 6Describe the pilot and what it changed (4 marks)
• 7Compare two sampling techniques for this study (5 marks)
• 8Eliminate the wrong tests and justify the right one (6 marks)
• 9Suggest three improvements, each with a reason (6 marks)

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Worked examples (9)

• 1Calculate the mean (2 marks)
• 2Calculate the range and give its limitation (3 marks)
• 3Calculate the standard deviation with the n − 1 formula (4 marks)
• 4Identify the correct graph and justify it (3 marks)
• 5Correct a badly drawn scatter graph (4 marks)
• 6Describe what the scatter graph shows (4 marks)
• 7Choose between the mean and the median (4 marks)
• 8Comment on the data without overstating it (5 marks)
• 9Interpret an unfamiliar table of descriptives (6 marks)

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Worked examples (9)

• 1Rank a set of scores containing ties (3 marks)
• 2Calculate d and d² from two rank columns (3 marks)
• 3Calculate rₛ from a given Σd² (3 marks)
• 4Complete a full Spearman calculation (5 marks)
• 5Decide significance from the critical value table (3 marks)
• 6Explain why Spearman and Wilcoxon point opposite ways (3 marks)
• 7Find the errors in a student's calculation (4 marks)
• 8Write a complete conclusion (5 marks)
• 9Distinguish strength from significance (5 marks)

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Worked examples (9)

• 1Give one strength of the design, with a reason (3 marks)
• 2Explain why causation cannot be inferred (4 marks)
• 3Evaluate the reliability of the sleep measure (4 marks)
• 4Evaluate the validity of the irritability measure (4 marks)
• 5Explain restriction of range and its effect (4 marks)
• 6Suggest two improvements, each with its cost (5 marks)
• 7Say which way each limitation pushes the result (5 marks)
• 8Reject a bad improvement and give a better one (4 marks)
• 9Reach a ranked judgement about the limitations (6 marks)

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