(c) Experiment

Only the experimental method, with its controlled manipulation of the independent variable and random assignment to groups, can establish cause-and-effect relationships.

(c) A strong negative relationship

The magnitude \(|r| = 0.85\) indicates a strong relationship. The negative sign means that as one variable increases, the other decreases.

(d) Standard Deviation

Standard deviation is a measure of variability (dispersion), not central tendency. It measures how spread out the data values are from the mean.

(b) Debriefing

Debriefing involves explaining the true nature and purpose of the study to participants after their participation, especially if any deception was used.

(c) Case study

A case study is an intensive investigation of a single individual (or a small group), using multiple sources of data like interviews, observations, and records.

Example: In a study on the effect of sleep on memory:

• IV: Number of hours of sleep (e.g., 4 hours vs. 8 hours)
• DV: Score on a memory test

The researcher manipulates the amount of sleep and measures how it affects memory performance.

Correlation indicates that two variables are related — they tend to change together. However, this does not mean that one causes the other.

Example: There is a positive correlation between ice cream sales and drowning incidents. This does not mean ice cream causes drowning. Both are influenced by a third variable — hot weather. People buy more ice cream and swim more in summer, leading to both higher sales and more drowning incidents.

To establish causation, one would need a controlled experiment where the independent variable is manipulated and all other variables are kept constant.

Reliability: A test is reliable when it produces consistent and stable results across different occasions, raters, or versions.

• Example: If a student takes an IQ test on Monday and again on Friday, a reliable test should give similar scores both times.

Validity: A test is valid when it measures what it claims to measure.

• Example: An intelligence test is valid if it truly measures intelligence and not just memory or vocabulary.

A test can be reliable but not valid (consistently measuring the wrong thing), but a valid test must also be reliable.

The Experimental Method is the most rigorous method in psychology, designed to establish cause-and-effect relationships.

Key Features:

1. Manipulation of the IV: The researcher deliberately changes one variable (IV) to observe its effect on another variable (DV).

2. Control of extraneous variables: Other variables that could affect the DV are kept constant or controlled.

3. Random assignment: Participants are randomly assigned to the experimental group (receives the treatment) or the control group (does not receive the treatment).

4. Measurement of the DV: The outcome is objectively measured.

Example: To test whether meditation reduces anxiety:

• IV: Meditation (practised vs. not practised)
• DV: Anxiety score on a standardised scale
• Experimental group: Practises 20 minutes of meditation daily for 4 weeks
• Control group: Does not practise meditation
• After 4 weeks, anxiety scores of both groups are compared.

Strengths:

• Can establish cause-and-effect
• High control over variables
• Replicable — other researchers can repeat the study
• Results can be statistically analysed

Limitations:

• Artificial setting may reduce ecological validity (results may not generalise to real life)
• Ethical issues: Some variables cannot be manipulated for ethical reasons (e.g., deliberately causing stress)
• Demand characteristics: Participants may guess the purpose and alter their behaviour
• Experimenter bias: The researcher’s expectations may unconsciously influence results

Psychological research involves human participants, so researchers must follow strict ethical guidelines to protect their rights and well-being.

Key Ethical Issues:

1. Informed Consent: Participants must be given clear information about the purpose, procedures, risks, and benefits of the study. They must voluntarily agree to participate.

2. Confidentiality: All personal data collected must be kept private. Participants should not be identifiable in published reports.

3. Right to Withdraw: Participants must be free to leave the study at any time without penalty or negative consequences.

4. Freedom from Harm: Participants should not experience physical or psychological harm. If any risk exists, it must be minimised and clearly communicated.

5. Debriefing: After the study, participants should be informed about its true purpose, especially if deception was involved.

6. Minimal Deception: Deception should be avoided whenever possible. If it is necessary (e.g., to prevent demand characteristics), it must be justified, and participants must be debriefed afterwards.

7. Competence: Researchers must possess the necessary skills, training, and qualifications to conduct the study responsibly.

8. Special Populations: Extra care must be taken when studying children, mentally ill individuals, or other vulnerable groups, including obtaining consent from guardians.

Importance: Ethical guidelines ensure that the pursuit of scientific knowledge does not come at the cost of individual rights, dignity, and well-being.

(a) Both A and R are true and R is the correct explanation of A

Causation can only be established when the researcher manipulates one variable (IV) and measures the effect on another (DV) while controlling extraneous variables. In correlational research, no variable is manipulated — only the existing relationship is measured. Therefore, the reason correctly explains the assertion.

(i)

• Independent Variable (IV): Type of background noise (silence, soft music, loud traffic noise)
• Dependent Variable (DV): Score on the reading comprehension test

(ii) Random assignment is important because it ensures that each participant has an equal chance of being placed in any group. This helps to:

• Distribute individual differences (e.g., reading ability, intelligence) evenly across groups
• Reduce the influence of confounding variables
• Allow valid comparison of group outcomes

(iii) Yes, the researcher can reasonably conclude a causal relationship, because this is a true experiment:

• The IV (noise type) was manipulated
• Participants were randomly assigned to groups
• Extraneous variables were controlled (same reading material, same time duration)

However, she should also ensure the result is statistically significant and should acknowledge possible limitations (e.g., Hawthorne effect, demand characteristics).

(iv) The researcher should obtain informed consent — participants must be informed about the study’s purpose and procedures and must voluntarily agree to participate.

(i) Mean:

\[ \bar{x} = \frac{12 + 15 + 18 + 14 + 20 + 16 + 15}{7} = \frac{110}{7} \approx 15.71 \]

(ii) Median:

Arrange in ascending order: \(12, 14, 15, 15, 16, 18, 20\)

Since \(n = 7\) (odd), the median is the middle value (4th value):

\[ \text{Median} = 15 \]

(iii) Mode:

The most frequently occurring value is 15 (appears twice).

\[ \text{Mode} = 15 \]

(iv) Range:

\[ \text{Range} = X_{\max} - X_{\min} = 20 - 12 = 8 \]

(i) Suggested methods:

1. Survey (questionnaire): The principal can distribute a standardised anxiety questionnaire (e.g., a Likert-scale questionnaire on exam anxiety) to a large number of Class 11 students. This is suitable because it can quickly collect data from many students and identify patterns.

2. Interview (semi-structured): She can conduct one-on-one interviews with a smaller sample of students who report high anxiety. This is suitable because it provides in-depth understanding of personal experiences, feelings, and triggers that a questionnaire may miss.

(ii) Data types:

1. Survey: Primarily quantitative data — numerical scores on the anxiety scale that can be statistically analysed.
2. Interview: Primarily qualitative data — verbal descriptions, narratives, and insights that need thematic analysis.

(iii) Limitations:

1. Survey: Students may not answer honestly due to social desirability bias (they may underreport anxiety to appear strong) or may not understand questions correctly.
2. Interview: It is time-consuming and can only cover a small number of students. The interviewer’s presence may also influence students’ responses.