Quantitative and Qualitative Research

Theory vs. Hypothesis

• From last class…

• Good research is informed by theory, or “a unified explanation for discrete observations that might otherwise be viewed as unrelated” From theory, researchers deduce testable hypotheses

• Deduction: general to specific From observations, researchers can induce theory

• Induction: specific to general

• A hypothesis is a specific statement predicting some outcome of an experiment or connection between variables

Scientific Method

1. Formulate theories √

2. Develop testable hypotheses √

3. Conduct research, gather data

4. Evaluate hypotheses based on data

5. Cautiously draw conclusions

Two major approaches to conducting research

• Quantitative Deductive (general to specific)

• Have theory, want to gather observations or evidence to test it

Hypothesis-testing

• Qualitative Inductive (specific to general)

• Have interesting observations or evidence, want to build a theory to explain them

Hypothesis-generating

Two major approaches (cont.)

Quantitative: Measuring quantities of behaviors or responses - matter of degree

• Information (data) that can be expressed in numerical terms, counted, or compared on a scale

• Seeks numbers or data that can convert to numbers

Qualitative: Assessing the nature, quality, or themes of behavior or responses – matter of kind

• Information (data) that is categorical or descriptive, rather than numerical

• Seeks descriptions, or data in words

Examples of two major approaches

• Quantitative Self-report (e.g., surveys, interviews) Observational Performance

• Qualitative Self-report (e.g., surveys, interviews) Observational Case study Ethnography Content or narrative analysis Grounded theory

Questions for discussion

1. Which kind of data is more convincing to you, numbers or words? Imagine you had to make an important decision about patient treatment or a therapeutic intervention.

2. Why do you think the history of psychology has been dominated by the quantitative approach?

3. Which fields are more likely than psychology to have incorporated qualitative approaches?

Choosing participants for two major approaches

• The way in which a researcher selects people to participate in their study is called sampling

• Quantitative sampling More often use random sampling, in which all

people in population have same odds of being selected to participate

• Generally not open to change once study has begun

• Qualitative sampling More likely to use purposive sampling, in which

key informants are sought to participate• Participants may change during study

Marshall (1996) article

• Both quantitative and qualitative researchers do not give enough attention to sampling

• Major question: Why shouldn’t both approaches use the same sampling methods?

• Quantitative seeks to generalize result to whole population so random or representative sampling is used Sometimes quota or convenience

• Breadth• Qualitative seeks to gather gather result that offer insights

on a small group so purposive or judgment sampling is used Sometimes convenience or theoretical

• Depth

Final notes on both approaches

• Both approaches begin with literature reviews; quantitative more likely to replicate designs or previous research, qualitative more likely to use research to establish gaps

• The approaches can be used in a complementary fashion, together providing a fuller understanding of phenomena “Mixed methods” or “multi-method” approach

• Quantitative approach may be preferred if time and money are limited

• Quantitative approach may be preferred if audience seeks concise answer to their question

• Qualitative approach may be preferred if research is delving into brand new area or new field

• Qualitative approach may be more respectful to some cultures or to unknown populations