Research methods

• Parametric


  • Data is normally distributed (the majority of data falls around average value)
  • Independent data collected from a population (one data point is not related to another)
  • Homogeneity of variance in groups (groups have similar spreads of data)
  • Interval scale: identity, order, & equal distance between numbers
  • Ratio scale: interval scale characteristics plus true zero; weight & height
  • More powerful for detecting differences
• Nonparametric


  • Doesn't make assumptions
  • No shape distribution; no normality
  • No population parameter
  • Nominal & ordinal scales: categorical data
• parametric/Nonparametric statistical tests

  • Independent T (A2) - Mann-Whitney U
  • Dependent T (A2) - Wilcoxon Matched Pairs
  • One-way ANOVA (A3) - Kruskal-Wallis
  • Two-way ANOVA (A3xB2) - Friedman's Matched Groups
  • Pearson Product Moment - Spearman Rank Order
• Eye color and hair color relationship


  • PPM – Spearman Rank Order
• Vision vs no vision effect on anticipation time, within-subjects


  • Dependent t – Wilcoxon Matched Pairs
• MCAT scores of female and male APK majors

  • Independent t- Mann-Whitney U
• VO2 max and three types of anaerobic exercise


  • One-way A3 ANOVA – Kruskal-Wallis
• Young, middle-aged, and elderly tested before and after a treatment

  • two-way (A3xB2) ANOVA – Friedman's Matched Groups
• What is the effect of four dosages of glucocorticoids on muscle wasting?


  • One-way ANOVA -Kruskal Wallis
• Does standing at a desk help people lose weight? Same people in standing and sitting groups

  • dependent t – Wilcoxon Matched pairs
• Does standing at a desk help people lose weight? Different people in standing and sitting groups


  • Independent t – Mann-Whitney U
• How much protein (15 vs 30 g) should people drink after moderately exercising for an hour? Compare baseline 30 min post, and 45 min post

  • Two-way ANOVA – Friedman's Matched Pairs
• ANCOVA


  • Parametric statistical analysis for removing the effects that is highly correlated with the dependent variable
  • Determine group differences beyond covariate
  • Removes covariate effects
• examples of ANCOVA

  • Pretest scores are correlated with posttest scores
  • Intelligence is highly correlated with reading ability

• Steps involved in ANCOVA


  1. Calculate correlation of variable with outcome measure (r2)

  2. Report calculated correlation

  3. Report original means

  4. Report covariate means
• Hick-Hyman Law


  • Movement decisions vary how we process information
  • IF YOU HAVE MORE OPTIONS = YOU TAKE MORE TIME
  • Reaction time (outcome measure) increases by 150ms
  • Uncertainty increases by 1 bit (bit = binary digit)
  • Simple choice = 0 (2^0=1)
  • 2 choice RT = 1 bit (2^1 = 2)
  • Three exceptions: Incompatible stimulus-response alignment, Highly practiced tasks, Stimulus-response alignment
• Research Methods: Four Criteria Review


  • Scientific quality
  • Logical organization
  • Writing clarity: coherent, clear, concise
  • Experimental design
• Scientific quality


  • Is the problem unique?
  • Is knowledge gap identified and answered?
  • Has published literature been critically analyzed?
  • Has literature been integrated and synthesized
  • How important is problem
  • Will study contribute to the literature
• Logical organization


  4 sections of a paper: Intro/Abstract, Methods, Results, Discussion
• Experimental design


  • How many factors, how many levels of each factor? Between or within subjects?
  • True experiment needs manipulation and randomization of IV and a control group
• Threats to internal and external validity


  • Internal: Maturation, history, testing, selection, regression, mortality, instruments
  • External: Selection x Rx, Setting x Rx, History x Rx, Multiple Rx interference
• Relationship between science, statistics, experimental design and variability


  Explaining variability is the goal of science. Statistics are used to evaluate patterns of availability. Variability arises from IV manipulation and human error
• ORCID Record

  
  

  Open researcher and contributor ID

  increase demand for researchers

  all funded UF researchers required to share ORCID record
• ethical principles

  
  

  ensure accuracy, protect intellectual property rights, unethical actions (fabricate, falsify, plagiarize), publication credit, reviewers respect confidentiality
• Five Institutional Review Boards at UF

  
  

  KNOW: IRB-02: behavioral and non-medical studies, rights and welfare of human participants must be upheld
• Tuskegee Study

  
  

  deliberately held information from participants about syphilis treatment even after it was widely available
• Potential threats to Internal Validity


  • Hawthorne effect: subject's behavior is altered by observation
  • Rosenthal effect (Pygmalion): higher expectations placed upon people lead to higher performance
• Multivariate Statistics


  • Inferential statistical procedures for analyzing two or more dependent variables on participants
  • Multiple regression and correlation
  • Meta-analysis
  • Canonical Correlation
  • Discriminant function analysis
  • Factor analysis commonalities
  • MANOVA
• Regression Analysis


  • What is the relationship between Y and X?
  • Simple regression: one predictor variable
  • Residual: how much the actual data point deviates from the model?
  • R^2: coefficient of determination
  • How much variance is explained
  • Closer to 1 = more variance explained
  • Multiple regression: Two or more IV on one DV
• Fitt's Law


  • Movement time is a function of the amplitude or distance of the required movement & the accuracy required at the time of movement
  • Speed accuracy trade off. Faster = less accurate
• Research Approaches


  Bench to Beside: taking studies from the lab and test treatments on human health protocols
• Clinical Trial Stages Phase 1

  • Purpose: Rx evolution
  • Participants: multiple replications
  • research methods: small group designs/within subjects/repeated measures,
  • Outcomes: individual Rx/performance based/quantify Rx effect
  • Limitations: high impact publication/less rigorous unscientific
• Writing Persuasive Arguments (MAGIC)


  • Magnitude
  • Articulation
  • Generality
  • Interestingness
  • Credibility
• Young Scientist Responsibilities

  Ask critical questions:

  • What experiment could disprove your hypothesis?
  • What hypothesis does your experiment disprove?

  Thoughts are principled arguments.

  Make an argument with supportable premise.
• Clinical research categories


  • Drug discovery and development
  • Treatment efficacy and effectiveness
  • Rehab efficacy and effectiveness
• Hypothesis Testing


  • Research hypothesis is a written statement that proposes a solution to the research question
  • Null Rx = 0
  • Alternative Rx ≠ 0
  • Significance = calculated value > critical value
  • Calculated F = treatment S^2 / error S^2
  • correlation: H0 p=0, H1 p/= 0
• Clinical Trial Stagesphase 2


  • Purpose: Rx efficacy
  • Participants: human groupings
  • research methods: medium group designs/randomized groups,
  • Limitations: problem identifying outcome measures/journals decline/data misinterpreted,
• Clinical trial phase 3

  • Purpose: Rx effectiveness
  • Participants: human populations
  • research methods: large group designs, multisite RC trial
  • outcomes: health status and impact on society
• health services research clinical trials


  purpose: delivery method

  participants: populations and institutions

  research methods: large group designs, population, and institutions

  outcomes: institutional and impact on society

  limitations: vulnerable to political policy debate, data misused
• Bimanual movements 


  The study concluded that elderly adults face increased bimanual motor performance, especially in asymmetrical tasks compared to younger counterparts. The study also found that older adults show less accuracy and longer completion times during the motor tasks.