1 / 9

Statistics

Statistics. “There are three kinds of lies: lies, damned lies and statistics”. # 4 out of 5 dentists recommend Dentyne # Almost 85% of lung cancers in men and 45% in women are tobacco-related. # Condoms are effective 94% of the time.

isolde
Télécharger la présentation

Statistics

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. Statistics “There are three kinds of lies: lies, damned lies and statistics”

  2. # 4 out of 5 dentists recommend Dentyne # Almost 85% of lung cancers in men and 45% in women are tobacco-related. # Condoms are effective 94% of the time. # Native Americans are significantly more likely to be hit crossing the streets than are people of other ethnicities. # People tend to be more persuasive when they look others directly in the eye and speak loudly and quickly. # Women make 75 cents to every dollar a man makes when they work the same job. # A surprising new study shows that eating egg whites can increase one's lifespan. # People predict that it is very unlikely there will ever be another baseball player with a batting average over 400. # There is an 80% chance that in a room full of 30 people that at least two people will share the same birthday. # 79.48% of all statistics are made up on the spot.

  3. Statistics are everywhere! • Health • Food • Sports • Politics • Science

  4. Misuse of statistics • Discarding unfavourable data • Loaded questions • Overgeneralisation • Biased samples • Misreporting / misunderstanding error • False causality • Proof of null hypothesis • Data dredging • Data manipulation

  5. Statistics in science

  6. Spreadsheets..  • Numerical bugs • Problems with blank cells • Typing mistakes • Circular references • The beginning of time (1900) • Bad graphics • Poor statistics

  7. Spreadsheets • Excel  • Openoffice  http://www.openoffice.org/ • Gnumeric  http://projects.gnome.org/gnumeric/

  8. P < 0.05 • In statistical hypothesis testing, the p-value is the probability of obtaining a test statistic at least as extreme as the one that was actually observed, assuming that the null hypothesis is true. • The lower the p-value, the less likely the result, assuming the null hypothesis, so the more "significant" the result, in the sense of statistical significance. One often rejects a null hypothesis if the p-value is less than 0.05 or 0.01, corresponding to a 5% or 1% chance respectively of an outcome that extreme, given the null hypothesis.

  9. misunderstandings • The p-value is not the probability that H0 or H1 are true • The p-value does not indicate the size or importance of the observed effect • Biological vs. statistical significance

More Related