Research Methodology in CSD - Group Designs

research design

formulated plan that is executed in a highly-skilled manner

research designs include 5 things:

1. protocols for selecting participants 2. controls for extraneous variables 3. observation of variables 4. ensuring ethical procedures 5. implementing treatment

formulating hypothesis

a prerequisite for developing an adequate research design

hypothesis

a tentative explanation for an observation or clinician problem to be investigated

the quality of a research design is judged by the examiner's ability to do two things:

1. answer research question 2. control extraneous variables

A high level of __ ensures the relationship between the IV and DV, which can be interpreted

Internal validity

A high level of internal validity ensures the relationship between the __ and __, which can be interpreted

IV DV

when sampling from a population, choose all possible individuals who have at least (how many?) characteristics in common

one

when using sampling designs in CSD research, researchers must identify the population of __

interest

sample of individuals is taken from the __ population that only represents __ of the population

target part

the two goals for sampling are:

1. to extract a relatively small number of observations from population 2. use this sample as basis for valid generalization of population as a whole

sampling methods

protocols for gathering a sample from target population

simple random sampling

in this type of sampling, each individual is selected by a chance process

convenience sampling

in this type of sampling, participants are selected from a pool of individuals who are available because of close geographic proximity, etc.

how are participants selected in convenience sampling?

participants selected from a pool of individuals who are available because of close geographic proximity

How are participants selected in simple random sampling?

participant selected by chance process

practical constrains dictate that (which type?) of sampling is substitute for simple random sampling

Convenience sampling

What is a negative aspect of using convenience sampling?

Can severely limit researcher's ability to generalize results to a larger population

stratified sampling

in this type of sampling, the target population is divided into non-overlapping subpopulations; random sampling is then drawn from each subpopulation

how are participants selected in stratified sampling?

target population is divided into non-overlapping subpopulations; random sampling is then drawn from each subpopulation

Characteristics of participants affect the __ of the study

validity

__ of participants affect the validity of the study

Characteristics

authoritative resources

What you can use to aid in determining selection criteria of participants

proper selection of research participants can do two things:

1. affect generalizability 2. affect ability for others to replicate results

in terms of participant selection, what is most beneficial for clinical research?

when participants represent all persons at risk for the behavior/disease being studied

What is a representative sample?

when participants represent all persons at risk for the behavior/disease being studied

representative samples include individuals from each __ in the target population as __ to the study

Constituency appropriate

sample size

number of participants in the study

sample size contributes to the __ of a research design

power

what does the power of a research design refer to?

Its ability to find a treatment effect when one is present

Power can be determined by __

Computer-generated software programs

power

the ability to find a significant/remarkable finding when it is present, regardless of the nature of the study

sample size

the most important factor that affects the power of a design

what are the four factors that affect the power of a design?

1. internal validity 2. measurement reliability 3. choice of statistical test 4. sample size

most of the time, studies with more __ will have more power to identify effects accurately when there are significant findings

participants

representative sample

type of sample when participants represent all persons at risk for the behavior/disease being studied

Individual descriptions of participants to consider include (12) :

1. age 2. gender 3. severity 4. education 5. handedness 6. etiology 7. time post onset 8. time since onset 9. lateralization 10. localization of brain damage 11. vision 12. intelligence

what does a single group research design involve?

observing one group of participants in two or more conditions

single group research design

(type of design) observing one group of participants in two or more conditions

why are single group research designs considered weaker than others?

Because they lack scientific comparability

In single group research designs, there is no __ group and may lack control over some __ variables

comparison, extraneous

Two examples of single group research design:

1. pretest posttest 2. pretest observation, experimental treatment, posttest observation

What are 5 possible nuisance/extraneous variables in single group research designs?

1. history 2. maturation 3. multiple test interference 4. statistical regression 5. testing

what is the MOST serious problem of single research design studies?

No means of knowing if extraneous variables affected DV

two group research design

(type of study) observation of two groups at different levels of IV

what type of nuisance/extraneous variables are typically controlled in two group research designs?

time-related extraneous variables (maturation and history)

Which design is more common in CSD: parallel or crossover?

parallel

parallel

(type of design) participants assigned to one of two groups. one group receives treatment, the other group acts as control (possibly receives some sort of stimulation, but no actual treatment is delivered)

crossover

(type of design) participants alternate between treatment and control conditions

in crossover designs, each participant acts as their own __

Control

parallel/crossover) designs are more economical. Why?

Crossover; require less participants

multiple treatment interference effects

problem or nuisance/extraneous variable that could be found in crossover studies

independent research design

(type of design) requires random assignment of participants in experimental and control groups

what does randomization of participants ensure?

Comparability between groups

related research designs

another name for quasi-experimental research designs

related research design

(type of design) randomization is not possible because IV is the classification variable and cannot be manipulated

in related research designs, the use of ___ on several variables other than the classification variable [AKA ___] strengthens the design relative to making the groups more ___

1. matching 2. IV 3. equivalent

simple randomization

process where participants are assigned to groups one at a time based on a single sequence of random assignments

blinding

ensures that all participants will not influence the outcome

What are the 3 important reasons to use randomization?

1. adds validity to statistical tests 2. minimizes extraneous variables 3. reduce bias

2 goals of simple randomization:

1. balanced regarding individual characteristics 2. free of experimenter selection bias

allocation concealment/blinding

hiding assignment of participants to groups from investigators

concealment reduces overstatement of __ effects, and improves chances for reporting more __ outcomes

treatment, accurate

two groups must be equivalent to satisfy __ requirements

Comparability

if two group are not __ for relevant variables, then conclusions may be inaccurate

equivalent

how would group equivalence be achieved in a related research design? (2 steps)

1. identify relevant variables 2. match two or more groups of participants based on these variables

how would group equivalence be achieved in an independent research design?

random assignment

in pretest posttest designs, how is external validity weakened?

If pretest sensitizes participants

If the pretest sensitizes participants in a pretest posttest design, what will be weakened?

external validity

complex research design

(type of design) increase design complexity by adding conditions to IV, adding IVs, increasing number of groups, or a combination of above

what are the 4 ways that can one increase design complexity?

adding conditions to IV, adding IVs, increasing number of groups, combination of above

multivalent designs

(type of design) any design having more than 2 conditions of the IV

factorial designs

(type of design) all possible combinations of levels of 2 or more IVs

interaction of effects

examines how multiple variables jointly affect variables

what are you most interested in when looking at factorial designs?

The observed effect of one IV changing as the function of the second IV

factorial designs can encompass 3 types of designs:

Independent, related, mixed

mixed design

(type of design) combination of related and independent variables

factorial designs may also have additional __ for each variable

Levels

Factorial designs may also have additional __

IVs

in factorial designs, the number of possible __ increase as the number of IVs increase

Interactions

solomon four group design

adding a third control group which may not receive treatment

May have a variation of three group design especially when dealing with ___ children

language impaired

Having more than one comparison group yields more __ results than having just one comparison group

meaningful