Sexual Assault Research and Statistics: What they mean, where to find them and how to use them.

1. Sexual Assault Research and Statistics:What they mean, where to find them and how to use them. Mary Lancaster Hope Center for Personal Empowerment

2. Overview • Short course in epidemiology and statistical methods and jargon • Helping you become an informed reader • Sources of research and statistics • How to use the information to your advantage • Brief summary of selected research 1995-2002

3. Epidemiology • The study of the distribution and determinants of health related states and events in populations.

4. Population • Epidemiology is not concerned with individuals. • What is a population? • Geographic location • Ethnic or cultural background • Occupation • Behavior and lifestyle • Age • Gender

5. Health related states and events • The outcome of interest • Examples: • Life expectancy • Suicide • Injury • Acquiring the common cold • Recovering from a bacterial infection • Reducing blood pressure

6. Determinants • Factors which are capable of bringing about a change in health • Examples: • Influenza virus • Carcinogens • Vaccination • Lifestyle • Exercise; diet; seatbelt and helmet usage

7. Distribution • Frequency of occurrence may vary from one population to another

8. Distribution in Time

9. Distribution in Space

10. Measures of Frequency • Prevalence • Incidence

11. Prevalence • Prevalence=number of existing cases divided by the total population • Hair color survey • 120 people with brown hair • 500 total people • 120/500=0.24 or 24%

12. Incidence • Incidence = number of new cases in a given period of time divided by the total population at risk • Infection rate • 2390 persons consumed ground beef • 482 develop E. coli infection • 482/2390 = 5.6%

13. Uses of Epidemiology • Describes, quantifies and postulates causal mechanisms for health phenomena in populations. • Based on observation of associations between potential causes and the health outcome, control measures may be developed.

14. Epidemiologic Studies • Descriptive • Who, what and where? • Analytic • Why and how?

15. Descriptive Studies • Frequency of occurrence of a particular condition • Patterns of occurrence according to person, place and time

16. Event Frequency • Expected level • Endemic • Sporadic • Epidemic • Pandemic

17. Rates commonly used in epidemiology • Crude • Calculated for an entire population • Category-specific • Based on number of persons in category and number of cases occurring in that group • Age-adjusted • Allows for better comparisons when differences exist in the age distribution in the two populations being compared

18. Analytic Studies • Observational • Experimental

19. Analytic Studies • Observational Studies • Case-control studies • Cohort studies • Prospective • Retrospective

20. Slide courtesy of Dr. Fran Wheeler, University of South Carolina

21. Slide courtesy of Dr. Fran Wheeler, University of South Carolina

22. Slide courtesy of Dr. Fran Wheeler, University of South Carolina

23. Analytic Studies • Experimental Studies • Intervention Studies • Clinical Trials

24. Slide courtesy of Dr. Fran Wheeler, University of South Carolina

25. Smoking and Lung Cancer P-value=0.00000064 Doll, R., Hill, AB. 1950. Smoking and carcinoma of the lung: preliminary report. British Medical Journal. 2:739.

26. Generating a Sample • Random Sampling • Systematic Sampling • Convenience Sampling

27. STATISTICS!!

28. Descriptive Statistics • Describe the population of interest • Measures of Central Tendency • Mean • Median • Mode

29. Statistical Inference • Drawing conclusions about an entire population based on information obtained from a sample of that population • Determining that the results obtained in a study are not likely to be due to chance alone

30. Smoking and Lung Cancer P-value=0.00000064 Doll, R., Hill, AB. 1950. Smoking and carcinoma of the lung: preliminary report. British Medical Journal. 2:739.

31. Statistical Tests! • Look them up in the stats text of your choice • Analysis of Variance • T-test • Chi-square • Regression

32. iCaution! Correlation does not equal causation.

33. Measures of Association • Relative Risk (RR) • Cohort studies • RR = 1 rates same for both groups • RR>1 Exposed more likely to experience event of interest • RR<1 Unexposed more likely to experience event of interest

34. Measures of Association • Odds Ratio • Case-control studies • OR>1 relationship of event to exposure is unlikely due to chance

35. Interpreting Results • Bias • Tendency of measurement to deviate from true value • Confounding • Occurs when a variable related to the condition is associated with, but not a consequence of, the exposure under study • Effect Modification • The magnitude of the association between variables differs according to the level of a third variable

36. Reading the Literature • Parts of a paper • Abstract • Introduction/Background • Materials and Methods • Results • Discussion • References

37. Where do I find all this great information? • Government sites • Libraries • Other organizations • Internet searches

38. Government Agencies • US Department of Justice • http://www.usdoj.gov • http://www.ojp.usdoj.gov/bjs/ • Centers for Disease Control and Prevention • http://www.cdc.gov • National Center for Injury Prevention and Control

39. Libraries • Use your local librarians! • University of Illinois Library • http://www.library.uiuc.edu • Online searches for books and journal articles • Online with contact information for the corresponding author

40. Organizations • RAD programs • National Center for Victims of Crime • http://www.ncvc.org • National Center for Missing and Exploited Children • http://www.missingkids.org • New York City Alliance Against Sexual Assault • http://www.nycagainstrape.org

41. Organizations • American College of Obstetricians and Gynecologists • http://www.acog.com • Promote Truth • Online support and information for teens on sexual violence • http://www.promotetruth.org • Many many other organizations….

42. Internet Searches • Lots of hits when searching • Sites which do not believe rape exists

43. Using the Information • Grant proposals • Justify budget requests and keeping the program • Dispel myths • Inform the public and your students • Talking to the media • Program evaluation • Develop partnerships

45. Sexual Assault Statistics • Estimated 683,000 rapes annually • 16% of survivors report to the police • Over 50% of lifetime rapes occur before age 18. One third before age 12. • 28% of college women reported experience since age 14 that met legal definition of rape or attempted rape

46. A select review of recent research • UIUC Library search using Ovid • References with full text available online or found in a library open over the weekend • Published between 1995 and 2002

47. Sexual Assault and Physical Health: Findings From a Population-Based Study of Older AdultsMurray B. Stein, Murray B. and Elizabeth Barrett-ConnorPsychosom Med, 62(6): 838-843November 2000. • Survey of 1359 community-dwelling men and women in Rancho Bernardo, CA • 80% of cohort completed sexual assault questionnaire • Self-administered sexual assault questionnaire

48. Questionnaire Details • “In your lifetime, has anyone ever tried to pressure or force you to have unwanted sexual contact? (sexual contact: touching your sexual parts, you touching their sexual parts, or intercourse).” • Subjects who responded “yes” were included in the “sexually assaulted” group and were asked whether this was a repeated or isolated event, their age when this first occurred, and whether they had ever received counseling for this experience. • Blood pressure, height, weight, and fasting plasma glucose levels were also measured at this index visit.

49. Sexual Assault Exposure in Men and Women Table 1. Sexual Assault Exposure in Men and Women Stratified by Age. aPercentage of sexual assault–positive subjects. From:   Stein: Psychosom Med, Volume 62(6).November 2000.838-843

50. Congratulations!