Evoked Potential

Research

In Experimental Research, the researcher manipulates an IV (while controlling for potential EV) to examine what effect the manipulation has on DV. To establish a functional relation between the IV and DV. 
Hypothesis
  • Null Hypothesis - no relationship between variables
    • no difference in IQ between people between with X and Y
  • Directional Hypothesis - we state the direction of the relationship between two variables
    • X will have higher scores than Y on IQ tests
  • Non-directional hypothesis - we don't know and won't speculate about the direction of the relationship between two variables
    • There will be a difference in IQ scores between X and Y
IRB
  • ethical research when using humans as subjects
  • types of research that need IRB
    • biomedical
      • biology
      • drugs
      • devices
    • behavioral
      • surveys
      • experiment
      • questionnaires
      • all other types of human subject research
  • key elements of informed consent
    • explanation of procedurees
    • risks or discomforts
    • benefits
    • confidentiality
    • termination of participation
    • costs/compensation
    • questions/contact information
    • signatures and copy
Qualitative vs Quantitative
  • ​Qualitiative
    • open ended observation to obtain naturalistic data
    • DESCRIPTIVE overview of data/observation
    • SMALL sample
    • in-depth description of data/observation
    • finding themes, patterns and relationships
    • understand perspective: WHY a particular outcome
    • SUBJECTIVE
  • Quantitative
    • time tested research method
    • observations are MEASURED and EXPRESSED in NUMERICAL values
      • objective
      • systematic process
        • numerical dat is used to test the hypothesis
      • LARGE sample
    • statistical analyses of numerical data
    • understand cause-effect relation; WHAT causes an outcome
    • OBJECTIVE
Questions
  • What is the statement of the general problem? Is it justified with current literature?
  • Was the rationale for study logical and convincing? Give one reason why you think so
  • Did authors proved current, thorough, and accurate literature review?
  • State the aim/purpose and research questions/hypotheses of the study. What is your opinion of the research question?
  • Was the introduction clearly written and well organized? What would you change?
Research Design
  • specific plan for selecting the IV(s) & measures to assess the DV(s) in order to answer specific research questions about their relations
  • Two purposes of a design
    • To permit investigator to answer research questions
    • To control extraneous variance/noise (variables that could affect the outcome of the study)
  • Major Classification of Research Designs
    • Single Subject Designs (SSD) - purpose is to demonstrate a functional relationship between an INTERVENTION (IV) and a change in target behavior (DV)
      • behavior of one or few individuals is studied
      • each person's performance evaluated in detail to examine affects of IV on DV
      • repeated, systematic measurement of DV
        • before, during, after manipulation of IV
        • DV is usually a human characteristic/behavior
        • IV usually involves application of intervention
      • Types of SSD
        • A-B design
          • used to quickly assess the effects of a treatment
            • phase 1 (A)
              • measure baseline response
            • phase 2 (B)
              • introduce treatment while measuring response
            • Baseline - Intervention
              • get a baseline for trial 1 - 5 and then see what happens at interventional stage
              • like monitoring, trials at baseline and then a measured response after a change is made
                • can have a delayed effect
                  • effect happens after many trials
                • an immediate effect
                  • happens right after baseline trials
                •  small effect or large effect
                • variable baseline and intervention
                  • jagged, all over the place
                • stable baseline and intervention
                  • large jump to intervention then stable 
                • combined effects
                • baseline trend = intervention trend
                  • basically linear; x = y, y = x
                • baseline trend does not = intervention trend
        • Withdrawal Designs
          • A-B-A
            • simplest of single subject designs
            • repeatedly introduces and withdraws treatment
              • A - Baseline phase
              • B - Treatment phase
              • A - Withdrawal phase
            • Objective

          • A-B-A-B
            • most powerful demonstration of causality and functional relationship
            • withdrawal phase allows more reliable assessment of intervention effects
          • A-B-A-C
        • Multiple Baseline Designs
        • Multiple Treatment Design
    • Group Designs
      • Study one or more "large" subject groups to examine affect of IV on DV
      • Compare "average" performance
      • Between - Subjects Design - Treatment Based Design
        • primary purpose is to examine the effect of the IV on two or more groups of subjects
        • with intent to determine whether groups perform similarly or not
        • treatment research with a control group
          • experimental (target) group receives treatment
          • control group does not receive treatment
        • Experimental
          • experimental research comparing the performance of two or more groups on one experimental task or condition
            • example: do typically developing children and children with hearing impairment with hearing aids differ in their speech recognition
            • example: comparing young vs old in some aspects of hearing/listening skills 
      • Within - Subjects Design
        • purpose: compare the performance of a single group on 2 or more conditions
        • all subjects in the study receive all treatments or levels of a treatment
        • also called repeated measures design
        • the main advantage over the between subject design is that it requires fewer participants, making the process much more streamlined and less resource heavy
        • example: does the speech intelligibility or pre-school hearing impaired kids improve comparably after receiving phonological treatment one and phonological treatment two
        • example: does speech perception better in BTE than CIC in the presence of wind noise?
        • experimental design
          • all subjects receive all experimental tasks and/or all levels of one or more of the experimental tasks
          • example 1: development changes in ABR/OAE in children longitudinal or cross-sectional study
          • example 2: does the comprehension of oral directions differ as a function of input speech rate (slow, normal, fast)
      • Mixed - Subjects Design
        • studies that combine both between-subjects design component (have 2 or more groups) and within-subjects design component (all subjects in all groups receive all conditions or tasks in the experiment)
          • make comparisons between subjects/groups (is there difference between groups on task conditions)
          • make comparisons within subjects/groups (how do subjects within each group perform on each level of the IVs)
          • Mixed Subjects Studies can be
            • transmission studies
            • experimental (non-treatment) studies
  • Validity in Research Design
    • internal validity
      • internal validity is the confidence that we can place in the cause and effect relationship in a study
      • could there be an alternative cause that may explain my observations
    • external validity
      • external validity is the ability of the study to generalize
      • whether results obtained from a small sample group, often in laboratory surroundings can be extended to make predictions about the entire population
  • Counter balance
    • to minimize carryover effect/order effect
    • order in which the treatment or experimental conditions are administered
    • not practice if you have > 5 conditions: expensive and very time consuming
Research Strategies
  • Descriptive research
    • naturalistic/observational
      • no intervention in study, does not manipulate or control anything
      • simple observation
      • no manipulation of independent variable
    • survey research
      • asking rather than observing
      • obtain information about opinions
      • questionnaire
    • retrospective research
      • obtaining data from already existing clinical data/records
      • no direct experimental manipulation
  • Experimental research
    • bivalent experiments
      • study the effects of two values on one IV on DV
    • multivalent experiments
      • study the effects of several values of IV on DV
    • parametric experiments
      • simultaneous effect of more than on IV on DV
      • example: study the speech of hearing impaired listener would have to consider
        • level of background noise
        • distance between talker and listener
        • acoustic character of talkers speech
        • type and severity of hearing loss
        • amplification properties of HA
  • Combined experimental & descriptive
  • Correlation research
    • purpose is to investigate relations between/among 2 or more variables by measuring how changes in one variable (X) corresponds to another (Y)
      • three possible outcomes
        • positive correlations
          • both variables increase or decrease at the same time
        • negative correlations
          • indicates that as the amount of one variable increases, the other decreases (and vice versa)
        • no correlation
          • indicates no relationship between the two variables
    • CAUTION 1 - Correlation does not imply causation
      • if 2 variables are correlated it means there is an association, not necessarily a causal association
        • Home Computer -> Child's vocabulary
    • CAUTION 2 - "significant" correlations may be due to uncontrolled variables
      • association between X and Y may be spurious (lucky) because another variable may be responsible for moderating the association between X and Y
        • association between home computer use and vocabulary may be due to various other factors like parent education
Scale
  • ​Nominal
  • Ordinal
  • Interval
  • Ratio
Variables
  • anything that can be varied
  • Independent Variable - variables manipulated by the experimenter
    • experimental group (drug) vs control group (placebo)
    • hearing aids vs no hearing aids
    • slow stimulation rate vs fast stimulation rate
    • CAUSE
  • Dependent Variable - variables that respond to experimental manipulation
    • static admittance
    • speech in noise performance
    • wave V latency
    • EFFECT
  • Extraneous Variable - aka nuisance variable
    • Testing environment
    • Instructions
    • Monaural vs Binaural
    • Age
    • Motivation
Picture
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