1 / 28

Biostatistics - Concepts

Biostatistics - Concepts. Tudor Calinici – JPEMS 2014. Study types. Based on the researchers role Observational Experimental. Main domains of medical research. Types of studies. Based on study objectives Descriptive Analytical. Statistics. Descriptive Inferential. Study types.

drake-garner
Download Presentation

Biostatistics - Concepts

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Biostatistics - Concepts Tudor Calinici – JPEMS 2014

  2. Study types • Based on the researchers role • Observational • Experimental

  3. Main domains of medical research

  4. Types of studies • Based on study objectives • Descriptive • Analytical

  5. Statistics Descriptive Inferential

  6. Study types Based on the studied population • Exhaustive • Sampling

  7. Statistical objects Population Sample / representative sample

  8. Population vs. Sample • Use sample because • size • accessibility • Economical reasons • Financial reasons

  9. Studies Source: www.socialresearchmethods.net

  10. Representative sample • A good sample must provide an image about the population • Representative sample • quantitative condition • qualitative condition

  11. Types of samples - groups Representative sample Exposed – non-exposed Case - control

  12. Study types Based on the duration of data collection • Cross-sectional • longitudinal - retrospectiveor prospective

  13. Descriptive statistics • Characteristics – Variables • Quantitative; Qualitative Collecting data

  14. Descriptive statistics • To present data • Tables • Charts • Numeric characteristics

  15. Tables

  16. Frequency tables

  17. Contingency tables

  18. Charts • The representation of the data • Distribution • For frequency tables • For contingency tables

  19. Problem A randomized clinical trial (RCT) has been performed in order to test the efficacy of Metistatin (a statin - drug intended to lower blood cholesterol levels) versus Placebo for preventing major vascular events (nonfatal myocardial infarction, cardiac death, stroke) in diabetic patients. A number of 1198 patients with diabetes from several hospitals in England were included in the study sample. The study was conducted after the approval for marketing of this preparation. .

  20. Of interest for the study was whether Metistatinis superior to placebo (placebo - identical in appearance, size, taste to Metistatin, but lacking the active substance) in preventing major vascular events. A secondary objective has been to follow if Metistatin lowers cholesterol more than Placebo. Another question was “Is gender related to major cardiovascular events?” Every patient who entered the study was randomly allocated to one of two preparations: Metistatin 80 mg daily administered as a single dose, or placebo. The allocation of the two interventions was masked – the investigator was allocating for each eligible patient a code corresponding to one of the two interventions, found in opaque numbered sealed envelopes. The pharmacy of the hospital was making sure each patient would receive the correct intervention based on the codes.

  21. Neither the patients nor the physicians were aware about which intervention the patients were receiving. Subjects were followed under similar care circumstances for all diabetic patients from the respective hospitals. The study excluded subjects receiving other medications that alter cholesterol levels (prednisone, estrogen, progesterone, anabolic drugs, and cyclosporine), subjects allergic to Metistatin, obese subjects and subjects for whom transportation for follow-up would be difficult or impossible. Also, all subjects who entered the study signed an informed consent (the act by which the patient consents to enter the study, acknowledging their rights, all the risks and benefits posed by his/her participation in the study). Patients were followed for 10 years. Blood cholesterol levels were measured at the beginning and at the end of the study and the occurrence of major vascular events has been recorded

  22. Exercise 1 • Describe the data collected in BD_Ten.xls file according to: • Gender • Treatment • Major vascular event • Treatment by gender • Major vascular event by gender

  23. Quantitative characteristics • Central Measures • Mean, median, mode • Spread Measures • Range, Standard Deviation, Coefficient of variation

  24. Normal distribution Sqew Kurt

  25. Qualitative characteristics • Prevalence • Incidence • Ratios • Odd Ratio • Risk Ratio

  26. Exercise 2 For qualitative variables compute the central measures, spread measures and decide if the data are normal distributed

  27. Inference Qualitative variables Chi Square test Quantitative variables T test for means

  28. Exercise Define research questions in terms of statistical hypothesis? Respond to the research questions!

More Related