Research Design Quantitative Study Design - B. Back to Class 9.

Research Design

Quantitative Study Design - B.

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Descriptive Study Designs

These studies are conducted to examine variables in naturally occurring situations. They look at relationships between variables as part of the overall descriptions but they do not examine the type or degrees of relationships. They protect against bias through conceptual and operational definitions of variables, sample selection, valid and reliable instruments, and control of the environment in which the data are collected.

Types of Descriptive Studies

Purely descriptive studies study the variables within a particular situation with a

single sample of subjects

Comparative descriptive studies examine the difference in variables between two or

more groups that occur in a particular situation

Time dimensional studies Longitudinal – changes in same subjects Cross-sectional – changes in groups of subjects at

different stages of development, simultaneously Trend – take samples of population at pre-set intervals Event partitioning

Descriptive Study Designs

Time dimensional cont.Retrospective studies – a manifestation of

some phenomena existing in the present is linked to phenomena occurring in the past.

Prospective studies – examine a presumed cause then go forward in time to the presumed effect. Its more costly and the researcher may have to wait a long time, but the correlation is stronger.

Descriptive Study Designs

Case study design Investigation of an individual, group, institution

or other social unit to determine the dynamics of what the subject thinks, behaves or develops in a particular manner. It requires detailed study over time. You can use any data collection method.

Strength – the depth of the study – it’s not superficial

Weakness – subjectivity of the researcher

Descriptive Designs cont.Survey Design

Research activity that focuses on the status quo of some situation. Information is collected directly from the group that is the object of the investigation by interview, telephone, internet, questionnaire. Purposes can be to:

describe – people’s characteristics, attitudes or beliefs – sub-samples may be compared

explain – a variable of interest by examining its relationship to other variables – nothing is manipulated

predict – people report their plans or intentions and extrapolations can be made

explore – use probing, loosely formulated questions to find out background data of subjects; to gain information to formulate research questions or hypotheses; to help develop theory for qualitative research

Strength – flexibility and broad scope Weaknesses – superficial, ex post facto, time and resources

Evaluation Research

An extremely applied form of Research that looks at how well a program, practice or policy is working. Its purposes are

To evaluate the success of a program, not why it succeeds, but whether it is succeeding

To answer practical problems for persons who must make decisions

Evaluation Research cont.

The classical approach Determine objectives of the program Develop means of measuring attainment of objectives Collect data Interpret data vies-à-vies the objectives

Goal-free evaluation Evaluation of the outcomes of a program in the absence

of information about intended outcomes Must describe the repercussions of a program or practice

or various components of the overall system

Categories of Evaluation

Formative evaluation – the ongoing process of providing evaluation feedback in the course of developing a program or policy (Process or Implementation)Summative evaluation – the worth of a program after it is already in operation – to help decide whether it should be discarded, replaced, modified or continued (Outcome Analysis – a. Impact b. Cost Comparative evaluation – assesses the worth of two or

more programs or procedures Absolute evaluation – assess the effects of a program in

and of itself – no contrast with other programs – called criterion-referenced – measures against criteria

Needs Assessment

Similar to evaluation research, it provides informational input in a planning process. It is usually done by an agency or group with a service component. It helps in establishing priorities. There are three approaches:

Key informantSurvey Indicators

Evaluation Research Weaknesses

Threatening to individuals

Seen as a waste of time

Role conflicts if researcher is in-house

Censor by “politicians” in-house

When some goals are satisfied and others are not, how is the whole thing evaluated

Goals may be for the future so can’t see outcome now

Other Types of Research

Secondary Analysis –studying data that have been previously gathered

Strength – it is efficient and economicalWeakness –

Variables may have been under analyzed You may want to look at different relationships

among variables You may want to change the unit of analysis You may want data from a sub-sample You may want to change the method of analysis

Other Types of Research

Replication Studies

Meta-analysis – merging findings from many studies that have examined the same intervention, then using statistics to determine overall effects of intervention.

Methodological – designed to develop the validity and reliability of instruments that measure constructs/variables. They are controlled investigations of ways to obtain, organize and analyze data.

Research Design Considerations

Research Control – the design should maximize the control an investigator has over the research situation and the variables. Rigor in quantitative control is exerted by the methodology used Constancy of condition – conditions under which

the data are collected must be as similar as possible

Environment Time, day, year One interviewer –if not minimize the variability Communication and treatment should be constant (same)

Research Design Considerations

Research control cont. Manipulation as control – ability to manipulate the

independent variable is very powerful Assures that conditions under which information was

obtained were constant or at least similar – can’t do that with ex-post facto research

Allows more difficult treatment because of control over it Can test two independent variables at the same time as

their effects

Research Design Considerations

Research control cont.Comparison groups as control – scientific

knowledge requires some type of comparison – even case studies have an implied reference – “normal”

Randomization as control – if you can’t randomize the subjects, then at least vary the order in which questions are asked – especially for attitudes

Research Design Considerations

Research control cont. Control over extraneous individual characteristics

of subjects Use only homogeneous subjects Include extraneous variables as independent variable –

randomly assign them to sub-blocks Matching – use knowledge of subjects from comparison

groups – matching on more than three characteristics is difficult. Matching may be done after the fact

Use statistical procedures (ANOVA) after the fact Use subjects themselves as their own controls Use randomization.

Research Design Considerations

Validity – the measure of truth or accuracy of a claim Internal validity shows that the findings are

due to the independent variable. It is maintained by using the controls on the previous slides, and by preventing threats to internal validity

Research Design Considerations

Threats to internal validity History – external threats which affect the

dependent variable Selection – biases from pre-treatment differences Maturation – within the subject over time – not

from the treatment Testing – the effect of taking a pretest on posttest

scores Mortality – loss of subjects during the study Other factors

Research Design Considerations

External validity – the generalizability of research findings to other settings or samples specifically to the population from which the sample came – there is no problem generalizing to the accessible population. Threats to external validity are:

Population factors: The Hawthorne effect – awareness of participation causes

different behavior Novelty effect – newness of the treatment might cause

alteration in behavior Placebo Effect

Research Design Considerations

External validity cont. Ecological Effects

Interaction between history and tresatment Interaction between selection and treatment Interaction between setting and treatment

Research Design Considerations

Experimenter effects – research is affected by characteristics of the researcher

Paradigm effect – basic assumptions and ways of conceptualization

Loose protocol – step-by-step detail not planned Miss-recording effect –especially if subjects record own

responses Unintentional expectancy effect – influences subjects

response Analysis effect – decide how to analyze after data collected Fudging effect – reporting effects not obtained

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