Regression

• How does correlation differ from regression?

  Correlation looks at the relationship between variables, while regression predicts one variable based on another.
• What question does regression specifically ask?

  How does variable x PREDICT variable y?
• What does correlation tell you when you have data for both age and height?

  Correlation tells you the strength of the relationship between age and height.

  
• How can regression be used in predicting height?

  Regression can be used to make a simple prediction about a child's height for the next year.

  
• What is multiple regression used for?

  Multiple regression is used to quantify how much various variables influence height and their relative degrees.
• What are independent variables now referred to as?

  Predictor variables
• What are dependent variables now referred to as?

  Outcome/criterion variables
• What does the overall model fit in regression represent?

  It is represented by R/R squared.
• What do beta values (β) indicate in regression?

  Beta values indicate the strength and direction of predictors.
• What does a positive beta value indicate?

  A positive beta indicates a positive predictor.
• What does a negative beta value indicate?

  A negative beta indicates a negative predictor.
• What is the purpose of Generalized Linear Models (GLM) in regression?

  GLM tests a linear model to predict values of an outcome variable from one or more predictor variables.
• What is a single regression?

  A single regression involves one predictor variable.

  
• What is multiple regression?

  Multiple regression involves more than one predictor variable.
• What does Y represent in regression?

  Y represents the dependent variable, which is the outcome you want to predict.

  
• What does β0 represent in regression?

  β0 represents the intercept, the value of Y when X is 0.

  
• What does β1 represent in regression?

  β1 represents the slope, indicating the change in Y for a one-unit change in X.
• What does ε represent in regression?

  ε represents the error term, the difference between the observed and predicted variables.

  
• What does R squared indicate in regression?

  R squared indicates how close each of the data points is to the regression line.
• What does the p-value indicate in regression?

  The p-value indicates the overall model fit and whether using the model is better than using the observed outcome variable mean.
• What does r squared measure in regression?

  r squared measures the goodness of fit, indicating how much of the outcome variable variance is explained by the predictors.
• What does the unstandardized beta (β) indicate?

  The unstandardized beta indicates the direction and strength of the relationship.
• What does the standardized beta (b) indicate?

  The standardized beta indicates how multiple predictors compare in terms of importance.
• What is a caution to consider in regression analysis?

  The global context of data is key in regression analysis.
• What is the main topic of the study material?

  Comparing means
• What are the learning objectives of the study material?

  • How to compare means for statistical significance
  • Theory and assumptions behind independent samples t-test
  • How to conduct a t-test in SPSS
• What are some examples of comparing means mentioned in the study material?

  1. Treatments (cognitive therapy) vs no treatment for depression
  2. Treatment (antipsychotic) vs no treatment for schizophrenia
  3. Effect of mood (happy vs scared) on reaction time to emotional changes
• Why is comparing means important in experiments?

  It allows us to see if a change in an independent variable leads to a change in a dependent variable.
• What question is posed regarding the average height of men and women?

  Do men and women have the same average (mean) height?
• What is the goal when comparing the means of two groups?

  To find out if the mean of one group is equal to the mean of another group.
• What are the independent and dependent variables in the height comparison example?

  • Independent variable: sex (male and female)
  • Dependent variable: height (cm)
• What is the null hypothesis in the context of comparing means?

  The null hypothesis states that the means are equal: x̄1 = x̄2.
• What is the alternative hypothesis in the context of comparing means?

  The alternative hypothesis states that the means are not equal: x̄1 ≠ x̄2.
• What is the purpose of measuring many men and women in the height comparison example?

  To see if their data is from the same distribution or different distributions.
• What is the difference between a sample and a population in statistical terms?

  • Sample: a subset of individuals measured from the population
  • Population: all individuals of interest
• What is the issue with comparing means from samples?

  The two means could come from the same population, leading to misleading conclusions.
• What are descriptive statistics?

  • Numbers describing the sample
• What are inferential statistics?

  • Using descriptive statistics to infer about the population
• What is a problem with data from two samples?

  Data from two samples will give different means, even if they come from the same population.
• What do tests of significance help determine?

  • Whether there is a difference between the samples when there is no difference in the population