Universiteit Amsterdam: UVA: Checklists, Projects, Summaries & Vacancies

INTRODUCING BIVARIATE CORRELATIONS
A bivariate correlation or bivariate association, is an association that involves exactly two variables. The nature of the association can be described with scatterplots and the correlation coefficient. Associations between categorical variables are usually presented in a bar graph.

INTERROGATING ASSOCIATION CLAIMS
The two most important validities to interrogate are construct validity and statistical validity with an association claim. The construct validity checks how well each variable was measured. The statistical validity checks how well the data supports the conclusion.

There are five questions that can be asked in order to interrogate the statistical validity:

1. What is the effect size?
   The effect size is the strength of a relationship between two or more variables. Larger effect sizes allow more accurate predictions and large effect sizes are usually more important. Exceptions on this second rule depend on the

Construct validity refers to how well a study’s variables are measured or manipulated. There are three common types of measurement: self-report, observational and physiological. The conceptual definition, or construct, is the researcher’s definition of the variable in question on a theoretical level. The operational definition represents a researcher’s specific decision about how to measure of manipulate the conceptual variable.

SELF-REPORT
A self-report measure operationalizes a variable by reporting people’s answers to questions about themselves in a questionnaire or an interview. In research on children, self-reports may be replaced with parent reports or teacher reports.     

The problems with self-reports are the demand characteristics: a participant wants to be  a ‘good’ participant. People their self-perception is not always correct and the social desirability: people want to give a good impression about themselves.

OBSERVATIONAL MEASURES
An observational measure is sometimes also called

It is important to both produce and consume research. A research consumer is important, because to effectively know something or to put a theory or treatment in to use, it is imperative that the research consumer knows the evidence behind the evidence-based treatment. It is important to be able to decide how valuable and useful a research really is.

Both research producers and research consumers share an interest in psychological phenomena, such as behaviour or emotion. They also both share a commitment to the practice of empiricism: to answer psychological questions with systematic observations.

The cupboard theory is the idea that young animals (but also your dog) clings on to the caregiver because the caregiver provides food. The contact comfort theory is the idea that young animals (but also your dog) clings on to the caregiver because the caregiver provides warmth and contact comfort. These

COMPARE TWO GROUPS BY RANKING
Nonparametric statistical methods are inferential methods that do not assume a particular form of distribution (e.g: the assumption of a normal distribution) for the population distribution. The Wilcoxon test is the best known nonparametric method. Nonparametric methods are useful when the data are ranked and when the assumption of normality is inappropriate.

The Wilcoxon test sets up a distribution using the probability of each difference of the mean rank. This test has five steps:

1. Assumptions
   Independent random samples from two groups.
2. Hypotheses
   
   
   
3. Test statistic
   This is the difference between the sample mean ranks for the two groups.
4. P-value
   This is a one-tail or two-tail probability, depending on the alternative hypothesis.