Posted: March 8th, 2016

Explain and critically discuss the application of confidence intervals (CIs) to inferential testing. Your answer should explain what CIs are, their strengths and factors which influence the width of a CI.

• Hypothesis 1 (HYP 1): It is hypothesised that males will be older, on average, relative to females;
• Hypothesis 2 (HYP 2): It is hypothesised that workers who are full time employed will report volunteering fewer days in the past year overall, relative to participants who are not full time employed;
• Hypothesis 3 (HYP 3): It is hypothesised that participants reporting higher levels of social support will tend to report lower levels of psychological distress.

For the written response to this activity, you should address the following points as relates to each hypothesis:
• Identify the level of measurement of both the relevant variables;
• Using reference to both characteristics of the data and statistical tests, explain why
particular tests were selected to test the hypotheses; and
• Report the results of these tests and critically interpret the findings.

Although this survey of community volunteers in Australia collected a range of information, the current file includes a limited sub-set of variables. These include:
• ID: A numeric code (from 1 – 253) that uniquely identifies each participant.
• AGE: Age of the participant in number of years.
• SEX: Male = 1; Female = 2.
• EMPLOY: Employment status, whereby 0 = Full time employed and 1 = Not full time employed (including students, unemployed and looking for work, those not in the labour market);
• DAY_VOL: Number of days volunteered in the past year;
• SOC_SUPP: Perceived social support, measured using 5-items (e.g., “Whenever I am sad, there are people who cheer me up”) derived from the Berlin Social Support Scale1. Individual items are scored on a 4-point likert scale (1 = strongly disagree, 2 = somewhat disagree, 3 = somewhat agree, 4 = strongly agree) and are summed to create the total score. Higher scores indicate more social support.
• DISTRESS: General psychological distress, measured using the 10-item Kessler Psychological Distress Scale (K-10)2. An example item is “During the last 30 days, about how often did you feel hopeless?” Individual items are scored on a 5-point likert scale (1 = None of the time, 2 = A little of the time, 3 = Some of the time, 4 = Most of the time, 5 = All of the time) and are summed to create the total score. Higher scores indicate greater psychological distress.