1 / 10

Percentiles

Percentiles. Percentages. Latin roots Cent = one hundred Percent = by the hundred Comparing raw score with a conceptual scale of 100 points Provides a reference for any raw score in relation to the rest of the scores. Percentile.

sunee
Télécharger la présentation

Percentiles

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. Percentiles

  2. Percentages • Latin roots • Cent = one hundred • Percent = by the hundred • Comparing raw score with a conceptual scale of 100 points • Provides a reference for any raw score in relation to the rest of the scores

  3. Percentile • “Defined as a point or position on a continuous scale of 100 theoretical divisions such that a certain fraction of the population of raw scores lies at or below that point.” • 75th percentile • 50th percentile • 33rd percentile

  4. Percentile as a Standard Score • Standard score - score derived from raw data and has a known basis for comparison • Allows us to compare scores more easily • What is more meaningful? • Balance index of 3.5 • Score was in the 65th percentile

  5. Standard Scores • Allow us to • Evaluate raw scores • Compare two sets of data that are based on different units of measure • Example • 3.5 on balance index • 120 Ft. lbs. of isokinetic torque in quadriceps

  6. Problems of Interpretation • Problem occurs at extreme ends of the scale for data sets with large numbers of scores • Ceiling effect • Learning curve • Easier to make improvements at beginning and middle of curve • More difficult at top • Plateau in curve

  7. Common Percentile Divisions • Quartiles • Deciles

  8. Calculating Using Percentiles • Rank order distributions • 10, 9, 9, 7, 7, 7, 6, 5, 5, 5, 4, 4, 3, 3, 1 • N = 15 • What percentile is the score 6? • What about 5? • What about 7? • Calculating raw score from percentile

  9. Calculating Using Percentiles • Simple frequency distributions • add number in frequency column from score

  10. Summary • Converting raw scores to standard scores is common • Standard scores allow us to compare 2 sets of data based on different units of measure • Percentile scores are most common standard score used

More Related