Postgraduate Course

7. Evidence-based management: Research designs

Empirical circle

Postgraduate Course

Research designs: 4 elements

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Randomization

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Comparison

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Before vs after

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Prospective vs retrospective

Research designs: terms

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Randomized controlled study Controlled before-after study Cohort / panel study Before-after study Post-test only study Survey Case study

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Experiment Quasi-experiment Observational study Longitudinal study Cross-sectional study Qualitative study

CBA: controlled before-after study Postgraduate Course In a controlled before-after study two or more groups are compared with each other, usually comprising one group in which an intervention is carried out (experimental group) and one group where no or an alternative intervention is conducted (control group).

CBA: controlled before-after study Postgraduate Course =

Postgraduate Course

Better (but not always feasible): randomization

In the case of randomization, the groups compared with each other are selected entirely randomly, for example by drawing lots. This means that each participant (or other unit such as a team, department or company) has an equal chance of being in the intervention or control group. In this way, the influence of any distorting factors is spread over both groups so that these groups are as comparable as possible with each other with the exception of the intervention.

Randomized controlled study (RCT) Postgraduate Course =

Cohort / panel study

Postgraduate Course Longitudinal study where large groups of people or companies (cohort / panel) are followed over a long period to see (prospective) whether differences occur among the groups. Starting point: intervention/exposure (independent variable) =

Case-control study

Postgraduate Course Longitudinal study in which one group of people or companies with a particular outcome is compared retrospectively with a group that does not have this outcome. Starting point: outcome (dependent variable)

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VS

=

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VS

Examples of (flawed) case-control studies Postgraduate Course

Before-after study Postgraduate Course Study in which data are obtained or particular characteristics are measured of a population before versus after an intervention / exposure / event, to measure the effect or correlation.

versus

Posttest-only Postgraduate Course =

Cross-sectional study Postgraduate Course Study in which data of a statistically significant sample of a population (managers, CEO’s, employees) is gathered at one point in time. It provides a snapshot of the current condition but does not explain cause and effect.

Cross-sectional studies include surveys

Cross-sectional study Postgraduate Course

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?

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Case study Postgraduate Course Study in which a large number (qualitative or quantitative) of aspects of a single case (organization or team) was investigated in depth over a long period within the case’s own context.

Experimental research Postgraduate Course Experimental research refers to studies where the researcher manipulates one (or more) variable and controls the other variable(s) to determine whether there is a causal relation between the manipulated variable and the outcome.

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‘True’ experiment: RCT

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‘Quasi’ experiment: CBA

Observational research Postgraduate Course Observational research refers to studies where the researcher merely observes but does not intervene, with the intention of finding correlations among the observed data

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Natural experiment

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Cohort / panel study

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Case-control study

Qualitative research Postgraduate Course Qualitative research explores and tries to understand people's beliefs, experiences, attitudes, behaviour and interactions. It generates non-numerical data. The best known qualitative research-methods include in-depth interviews, focus groups, documentary analysis and participant observation. Qualitative research includes

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Case studies Ethnographic studies Field research Grounded theory approach

Longitudinal research Postgraduate Course A longitudinal study is an observational study that involves repeated observations (measurements) of the same variable(s) over long periods of time (sometimes years or even decades).

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Cohort / panel study

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Repeated measures

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Times series

Mixed methods Postgraduate Course

But ….

Postgraduate Course

Better than a single study: a replication study Better than a replication study: a systematic review / meta analysis

If there were 100 studies, 99 of which gave a ‘negative’ result (where, say, the new intervention appeared to be not effective) , while one had a ‘positive’ result (were the intervention appeared effective), it would obviously be a mistake to consider only the single positive study.

Systematic review / meta-analysis Postgraduate Course The intention behind a systematic review is to identify as fully as possible all the scientific studies of relevance to a particular subject and to assess the validity and authority of the evidence of each study separately. As the name indicates, a systematic review takes a systematic approach to identifying studies and has the methodological quality critically appraised by multiple researchers independently of each other, as a consequence of which the review is transparent and reproducible and can be monitored. The use of statistical analysis techniques in a systematic review to pool the results of the individual studies numerically in order to achieve a more accurate estimate of the effect is termed a “meta-analysis”.

Systematic review / meta-analysis Postgraduate Course ?

Which terms belong together?

Postgraduate Course 1.

Randomized controlled study 2.

Controlled before-after study 3.

Cohort / panel study A.

Experiment 4.

Before-after study 5.

Post-test only study B.

Quasi-experiment C.

Observational study 6.

Survey 7.

Case study D.

Longitudinal study E.

Cross-sectional study F.

Qualitative study