Title: List of psychological research methods
Content:  is obtained, how that information is sampled, and the types of instruments that are used in data collection. Methods also vary by whether they collect qualitative data, quantitative data or both. Qualitative psychological research is where the research findings are not arrived at by statistical or other quantitative procedures. Quantitative psychological research is where the research findings result from mathematical modeling and statistical estimation or statistical inference. Since qualitative information can be handled as such statistically, the distinction relates to method, rather than the topic studied. There are three main types of psychological research:  The following are common research designs and data collection methods:  Research designs vary according to the period(s) of time over which data are collected:  Research in psychology has been conducted with both animals and human subjects: 
Title: Psychological research
Content:  Psychologists use many research methods, and categorical distinctions of these methods have emerged. Methods can be categorized by the kind of data they produce: qualitative or quantitative—and both these are used for pure or applied research. Psychology tends to be eclectic, applying knowledge from other fields. Some of its methods are used within other areas of research, especially in the social and behavioural sciences.
Title: Psychology
Content:  Quantitative psychological research lends itself to the statistical testing of hypotheses. Although the field makes abundant use of randomized and controlled experiments in laboratory settings, such research can only assess a limited range of short-term phenomena. Some psychologists rely on less rigorously controlled, but more ecologically valid, field experiments as well. Other research psychologists rely on statistical methods to glean knowledge from population data. The statistical methods research psychologists employ include the Pearson product–moment correlation coefficient, the analysis of variance, multiple linear regression, logistic regression, structural equation modeling, and hierarchical linear modeling. The measurement and operationalization of important constructs is an essential part of these research designs. Although this type of psychological research is much less abundant than quantitative research, some psychologists conduct qualitative research. This type of research can involve interviews, questionnaires, and first-hand observation. While hypothesis testing is rare, virtually impossible, in qualitative research, qualitative studies can be helpful in theory and hypothesis generation, interpreting seemingly contradictory quantitative findings, and understanding why some interventions fail and others succeed.
Title: List of psychological research methods
Content: Correlational research ; Descriptive research ; Experimental research Archival research ; Case study – Although case studies are often included in 'research methods' pages, they are actually not a single research method. Case study methodology involves using a body of different research methods (e.g. interview, observation, self-report questionnaire). Researchers interpret what the data together mean for the area of study. So, case studies are a methodology, not a method. ; Computer simulation (modeling) ; Content analysis ; Event sampling methodology, also referred to as experience sampling methodology (ESM), diary study, or ecological momentary assessment (EMA) ; Experiment, often with separate treatment and control groups (see scientific control and design of experiments). See Experimental psychology for many details. ; Field experiment ; Interview, can be structured or unstructured. ; Meta-analysis ; Neuroimaging 
Title: List of psychological research methods
Content:  other psychophysiological methods ; Observational study, can be naturalistic (see natural experiment), participant or controlled. ; Program evaluation ; Quasi-experiment ; Self-report inventory ; Survey, often with a random sample (see survey sampling) ; Twin study Retrospective cohort study: Subjects are chosen, then data are collected on their past experiences. ; Prospective cohort study: Subjects are recruited prior to the proposed independent effects being administered or occurring. ; Cross-sectional study, in which a population are sampled on all proposed measures at one point in time. ; Longitudinal study: Subjects are studied at multiple time points: May address the cohort effect and indicate causal directions of effects. Animal study ; Human subject research A wide range of research methods are used in psychology. These methods vary by the sources from which 
Title: Developmental psychology
Content:  Developmental psychology employs many of the research methods used in other areas of psychology. However, infants and children cannot be tested in the same ways as adults, so different methods are often used to study their development. Developmental psychologists have a number of methods to study changes in individuals over time. Common research methods include systematic observation, including naturalistic observation or structured observation; self-reports, which could be clinical interviews or structured interviews; clinical or case study method; and ethnography or participant observation. These methods differ in the extent of control researchers impose on study conditions, and how they construct ideas about which variables to study. Every developmental investigation can be characterized in 
Title: Educational psychology
Content:  researchers. Quantitative research is the backing to most observable phenomena in psychology. This involves observing, creating, and understanding distribution of data based upon the study's subject matter. Researchers use particular variables to interpret their data distributions from their research and employ statistics as a way of creating data tables and analyzing their data. Psychology has moved from the "common sense" reputations initially posed by Thomas Reid to the methodology approach comparing independent and dependent variables through natural observation, experiments, or combinations of the two. Though results are still, with statistical methods, objectively true based upon significance variables or p- values.
Title: Psychological typologies
Content:  systems are more difficult in the absence of the reliable methodological base: there is not a generally accepted opinion on what to compare and how to estimate. For investigation the types it is necessary to be able to use both the qualitative and quantitative methods of empirical reality research, taking into account the following factors: 1. The scale and the complex character of research (the possibility of keeping under control several plans of different scales). 2. The character and specificity of distribution of properties and characteristics in the studied environment. 3. The adequate number of sub-scales, not violating the completeness and the constructive validity of a psychological traits.
Title: Wilhelm Wundt
Content:  Experimental psychology in Leipzig mainly lent on four methodological types of assessment: the impression methods with their various measurement techniques in psychophysics; the reaction methods for chronometry in the psychology of apperception; the reproduction methods in research on memory, and the expression methods with observations and psychophysiological measurement in research on feelings. Wundt considered the methodology of his linguistic psychological investigations (Vols. 1 and 2 of Völkerpsychologie) to be the most fruitful path to adequate psychological research on the thought process. The principles of his cultural psychological methodology were only worked out later. These involved the analytical and comparative observation 
Title: Case study in psychology
Content:  Case study in psychology refers to the use of a descriptive research approach to obtain an in-depth analysis of a person, group, or phenomenon. A variety of techniques may be employed including personal interviews, direct-observation, psychometric tests, and archival records. In psychology case studies are most often used in clinical research to describe rare events and conditions, which contradict well established principles in the field of psychology. Case studies are generally a single-case design, but can also be a multiple-case design, where replication instead of sampling is the criterion for inclusion. Like other research methodologies within psychology, the case study must produce valid and reliable results in order to be useful for the development of future research. Distinct advantages and disadvantages are associated with the case study in psychology. The case study is sometimes mistaken for the case method, but the two are not the same.

Question: two main types of research methods used in psychology?
Answer: quantitative data.
quantitative.
Quantitative psychological research.
qualitative.
Experimental research.
Qualitative psychological research.
qualitative data.
Correlational research.
Descriptive research.