PSY248 Lecture Notes - Lecture 2: Unimodality, Standard Deviation, Central Tendency
2 Jun 2018
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Correlation and Regression: Week 2 - PSY248
Before statistics;
• Step 1: understand the research question
• Step 2: how are DV and IV measured?
• Step 3: choose method of analysis (correlation/regression)
Conduct correlation/regression analysis;
• Part 1: univariate
• Part 2: bivariate
• Part 3: regression and check assumptions
Step 1 – understand the research question:
• Research – studying carers of people on home hemodialysis
• Research question – how much distress do home hemodialysis caregivers
experience, is this distress related to age of the carer, and can this distress be
predicted from information about the age of the carer?
→ Correlation asks is there a RELATIONSHIP between two variables
→ Regression refers to prediction
Research question in a diagram:
• IV = age of carer
• DV = carer distress
• 1. What is the level of carer distress? Does carer distress vary? (univariate)
o Produce descriptive statistics
• 2. Is carer distress (linearly) related to age of carer? (bivariate)
o Produce correlational statistics
• 3. Does knowledge about age help predict level of carer distress? (regression)
o Produce regression
• In this RQ, we want to know whether a carer’s age is useful in predicting their
distress
• This is NON-EXPERIMENTAL research
Step 2: how are the DV/IV measured?
• We look at
o How we intended to measure (questionnaire)
o What we actually ended up with (results – data)
• Decide level of measurement – categorical, ordinal or interval
• Then we need this to decide what statistical analysis to use
• This leads to either correlation/regression = IV/DV
continuous/interval/numeric and normal
• For instance:
o Age: categorical (young, middle, old), distress: categorical (low,
medium, high) = chi-square appropriate
o Age: categorical (young, middle, old), distress: numerical = one-way
ANOVA
o Age: numerical, distress: numerical = correlation/regression
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Document Summary
Before statistics: step 1: understand the research question, step 2: how are dv and iv measured, step 3: choose method of analysis (correlation/regression) Conduct correlation/regression analysis: part 1: univariate, part 2: bivariate, part 3: regression and check assumptions. Correlation asks is there a relationship between two variables. Iv = age of carer: dv = carer distress, 1. Does carer distress vary? (univariate: produce descriptive statistics, 2. Is carer distress (linearly) related to age of carer? (bivariate: produce correlational statistics, 3. Does knowledge about age help predict level of carer distress? (regression: produce regression. In this rq, we want to know whether a carer"s age is useful in predicting their distress: this is non-experimental research. Anova: age: numerical, distress: numerical = correlation/regression, specific health questionnaire; consisted of 15 items, study had age categories (one of 9) but we are going to treat them as continuous variables (numeric)
