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Research Methods

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Research Methods

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  1. Research Methods • in Marriage and Family Therapy • University of Guelph, Open Learning and Educational Support

  2. Today: Numbers

  3. Today • This Journal Has 22 Minutes • Clinical Trials • Meta-Analysis • Correlation & Prediction

  4. Please complete the RAT

  5. RAT Scores Day Three • Scores ranged between 25 – 34 • Mean score was 29.89 (1- 30.67; 2- 28.67) • SD was 3,81 (1 - 3.94; 2 - 3.71) • 68.26% of scores fall between 26.08 and 33.70 • 95.44% of scores fall between 22.27 and 37.51

  6. The DOG

  7. Advantages to Numbers • Easier to collect and score • Easier to determine improvement or decline • “Objective” = believable

  8. Disadvantages to Numbers • What do they mean? • Are they really believable? • Were you just being nice?

  9. RandomizedClinical Trials • Considered by many to be the “gold standard” of research • Almost necessary to show efficacy and effectiveness of treatment • Based on experimental design methodology

  10. RandomizedClinical Trials • Goal: compare a treatment group to a control group to determine difference in outcome • Assumes that one will be better than the other and lead to better outcomes • Most restrictive form of clinical trials • High control over extraneous variables

  11. RandomizedClinical Trials • Three basic elements: • Intervention and control treatment • Outcome measures • Randomization

  12. RCTs & Research Questions • Three possible questions: • Is X an efficacious treatment of _____ ? • Is X an effective treatment of _____ ? • Is intervention A more effective than intervention B in the treatment of ____ ?

  13. Definitions • Efficacy: How a treatment works in ideal circumstances, when delivered to selected patients by providers most skilled at providing it (usually relates to strict criteria of RCTs) • Effectiveness: How a treatment works under ordinary conditions by the average practitioner and delivery system for the typical patient • (Lyness, Walsh & Sprenkle, p. 302)

  14. Random Sampling • Ensures that each person in the population has an equal chance of being selected • Easier to justify statistically any generalizations made to a larger population

  15. Random Selection • Ensures participants have equal opportunity to be in either treatment or control group • Limits bias of allocation to a group • Produces comparable groups for testing • Validating statistical tests of significance (similar or equal size) • Matching should only be used with small sample sizes

  16. Sampling Biases • Allocation – when assignment influenced by investigator’s knowledge of treatment • Response – when participants know what group they are in • Assessment – when staff members know what group participants are in • Double-blind study is best but near impossible

  17. Variables • Independent – manipulated by researcher to produce outcomes (ie. Intervention) • Dependent – the outcome measures that should be affected by changes in the treatment • Supplementary (nuisance) – need to be controlled to prevent interference in interpreting group differences; can be controlled for statistically or by blocking

  18. Therapist Variables • Effectiveness – differences in the abilities of therapists • Allegiance – commitment to or belief in the treatment • Use the same therapist, match on allegiance and effectiveness, or perform statistical analyses to see if therapists differ significantly

  19. Ethical Considerations • Voluntary participation, informed consent • Do no harm • Anonymity, confidentiality

  20. Withholding Treatment • Is it unethical to put clients in a control group where they do not receive treatment?

  21. Alternatives toNo Treatment • Wait list • Treatment on demand • Parallel treatment group or add-on

  22. Data Collection • Stored in a secure location, limited access • All data files on computer should be password protected • No identifying information attached to the data

  23. Clinically Significant Change • Not enough to say that the experimental group has improved • As defined by Jacobson & Traux (1991):“the level of functioning subsequent to therapy places that client closer to the mean of the functional population than it does to the mean of the dysfunctional population”

  24. Strengths of RCTs • Can demonstrate the efficacy and effectiveness of interventions • Can determine comparisons between interventions • Political and economic implications of manualized treatment and evidence-based practice

  25. Weaknesses of RCTs • Costly and time-intensive • Demonstrate efficacy but not always effectiveness • Promotes homogeneity of treatment for problems that are not typically homogeneous • Contrast with findings of common factors research

  26. Statistics

  27. Everything you ever wanted to know... • http://www.statsoft.com/textbook/

  28. Studying the world • Variables (things you measure) • Experiment: do something and see what happens • Correlation: observe the world and see how things are related

  29. Types of Variables • Nominal - names, no order (Carl, William, Robert; male, female; single, married, divorced) • Ordinal - order, no interval (small, medium, large) • Interval - order, interval, no zero point (degrees C) • Ratio - order, interval and zero (degrees K, age, height, DAS score)

  30. Variables in Experiments • Independent - the ones you manipulate • e.g. EFT • Dependent - the results • e.g. Marital satisfaction

  31. Making sense of the numbers (interval, ratio) • If you take several measurements of the same thing, you tend to get the same result (central tendency)

  32. “Most people agree that Carl is a great guy. Some think that he is superlative. Some think that he is not so hot.” Frequency Value

  33. Mean • Me after ten p.m. • Measure of central tendency

  34. Mean Example: 12 students complete the RAT Their scores range from 23 to 32 The sum of all the scores divided by the number of scores = 27.9 This is the mean x = ∑x n The mean is a measure of central tendency

  35. “Three out of four classes agree that Carl is a great guy.”

  36. Standard Deviation This is a measure of the spread of the individual values away from the mean A large standard deviation means a lot of variation in the results A small standard deviation means that the mean is fairly representative of the value of the variable for that population

  37. Calculating Standard Deviation • Calculate the mean • Measure the difference of each value from the mean • Square the differences to get rid of the negatives • Find the mean of the squared differences • Take the square root

  38. Standard Error σ/√n Standard Deviation divided by the square root of the number of observations 95% confidence interval

  39. Type I Error • α or false positive = thinking there is an effect when there is none

  40. Type II error • β or false negative = thinking there is no effect of treatment when in fact there is

  41. Statistical terms • efficacy: capacity to produce an effect (ideal) • effectiveness: change under real-life conditions

  42. Mode • a) ice cream • b) the most frequently occurring value