showtime l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
SHOWTIME! PowerPoint Presentation
Download Presentation
SHOWTIME!

Loading in 2 Seconds...

play fullscreen
1 / 16

SHOWTIME! - PowerPoint PPT Presentation


  • 132 Views
  • Uploaded on

SHOWTIME!. STATISTICAL TOOLS IN EVALUATION. DESCRIPTIVE VALUES MEASURES OF VARIABILITY. MEASURES OF CENTRAL TENDENCY. WHEN THE GRAPH OF THE SCORES IS A NORMAL CURVE, THE MODE, MEDIAN, AND MEAN ARE EQUAL THE MEAN IS THE MOST COMMON MEASURE OF CENTRAL TENDENCY

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

SHOWTIME!


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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
statistical tools in evaluation

STATISTICAL TOOLS IN EVALUATION

DESCRIPTIVE VALUES

MEASURES OF VARIABILITY

slide3

MEASURES OF CENTRAL TENDENCY

  • WHEN THE GRAPH OF THE SCORES IS A NORMAL CURVE, THE MODE, MEDIAN, AND MEAN ARE EQUAL
  • THE MEAN IS THE MOST COMMON MEASURE OF CENTRAL TENDENCY
  • WHEN THE SCORES ARE QUITE SKEWED OR THE DATA IS ORDINAL LACKING A COMMON INTERVAL, THE MEDIAN IS A BETTER MEASURE OF CENTRAL TENDENCY
  • THE MODE IS USED ONLY WHEN THE MEAN OR MEDIAN CANNOT BE CALCULATED (E.G., NOMINAL DATA) OR WHEN THE ONLY INFORMATION WANTED IS THE MOT FREQUENT SCORE (E.G., MOST UNIFORM SIZE OR INJURY SITE)
measures of variability
MEASURES OF VARIABILITY
  • DESCRIBES THE SET OF SCORES IN TERMS OF THEIR SPREAD, OR HETEROGENEITY

• CONSIDER TWO GROUPS OF SCORES

GROUP 1 = 9, 5, 1; GROUP 2 = 5, 6, 4

• BOTH HAVE A MEAN AND MEDIAN OF 5 BUT GROUP 2 HAS MUCH MORE HOMOGENEOUS OR SIMILAR SCORES THAN GROUP 1

measures of variability5
MEASURES OF VARIABILITY
  • RANGE
  • STANDARD DEVIATION
  • VARIANCE
range
RANGE
  • EASIEST MEASURE OF VARIABILITY TO CALCULATE
  • USED WHEN THE MEASURE OF CENTRAL TENDENCY IS THE MODE (NOMINAL DATA OR WHEN THE MOST FREQUENT SCORE IS OF INTEREST) OR MEDIAN (ORDINAL DATA OR SKEWED DATA)
  • SIMPLY THE DIFFERENCE BETWEEN THE HIGHEST AND LOWEST SCORES
what is the range in the set of scores below
WHAT IS THE RANGE IN THE SET OF SCORES BELOW?
  • SET OF SCORES:

7, 2, 7, 6, 5, 6, 2

RANGE = HIGHEST SCORE MINUS LOWEST SCORE = 7 - 2 = 5

standard deviation s
STANDARD DEVIATION (S)
  • MEASURE OF VARIABILITY USED WITH THE MEAN (NORMALLY DISTRIBUTED INTERVAL OR RATIO DATA)
  • INDICATES THE AMOUNT THAT ALL SCORES DIFFER OR DEVIATE FROM THE MEAN
  • THE MORE THE SCORES DIFFER FROM THE MEAN, THE HIGHER THE STANDARD DEVIATION (S)
  • SUM OF THE DEVIATIONS OF SCORES FROM THE MEAN IS ALWAYS IS 0
definitional formula for standard deviation
DEFINITIONAL FORMULA FOR STANDARD DEVIATION
  • FORMULA 2.1 SHOULD BE USED IF THE GROUP TESTED IS VIEWED AS THE GROUP OF INTEREST; CONSIDERED THEN THE POPULATION (E.G., CALCULATING STANDARD DEVIATION OF THE TEST SCORES ON EXAM #1 IN THIS CLASS)
  • X = SCORES
  • BAR X = MEAN OF SCORES
  • N = NUMBER OF SCORES
  • MANY CALCULATORS USE THIS FORMULA
definitional formula for standard deviation10
DEFINITIONAL FORMULA FOR STANDARD DEVIATION
  • FORMULA 2.2 SHOULD BE USED IF THE GROUP TESTED IS VIEWED AS A REPRESETATIVE PART OF THE POPULATION; CONSIDERED THEN A SAMPLE
  • STANDARD DEVIATION CALCULATED ON THE SAMPLE IS USED AS AN ESTIMATE OF THE POPULATION STANDARD DEVIATION (E.G., CALCULATION OF THE STANDARD DEVIATION OF THE PERCENT BODY FAT OF COLLEGE RUNNERS THAT IS USED AS AN ESTIMATION OF THE STANDARD DEVIATION OF ALL COLLEGE RUNNERS)
  • X = SCORES
  • BAR X = MEAN OF SCORES
  • N = NUMBER OF SCORES
  • MANY CALCULATORS AND MOST COMPUTER PROGRAMS USE THIS FORMULA
slide11
SAMPLE CALCULATION OF THE STANDARD DEVIATION USING FORMULA 2.1 AND 2.2 AND THE FOLLOWING TESTS SCORES: 7, 2, 7, 6, 5, 6, 2
calculational formula for standard deviation
CALCULATIONAL FORMULA FOR STANDARD DEVIATION
  • FORMULA 2.3 SHOULD BE USED IF THE GROUP TESTED IS VIEWED AS THE GROUP OF INTEREST; CONSIDERED THEN THE POPULATION (E.G., CALCULATING STANDARD DEVIATION OF THE 50-M SWIM TIMES AT A SWIM MEET )
  • X = SCORES
  • N = NUMBER OF SCORES
  • FORMULA TYPICALLY USED FOR HAND CALCULATION
calculational formula for standard deviation13
CALCULATIONAL FORMULA FOR STANDARD DEVIATION
  • FORMULA 2.4 SHOULD BE USED IF THE GROUP TESTED IS VIEWED AS A REPRESETATIVE PART OF THE POPULATION; CONSIDERED THEN A SAMPLE
  • STANDARD DEVIATION CALCULATED ON THE SAMPLE IS USED AS AN ESTIMATE OF THE POPULATION STANDARD DEVIATION (E.G., CALCULATION OF THE STANDARD DEVIATION OF THE 40-YARD TIME OF COLLEGE WIDE RECEIVERS THAT IS USED AS AN ESTIMATION OF THE STANDARD DEVIATION OF ALL COLLEGE WIDE RECEIVERS)
  • X = SCORES
  • N = NUMBER OF SCORES
  • FORUMULA TYPICALLY USED FOR HAND CALCULATION
slide14
SAMPLE CALCULATION OF THE STANDARD DEVIATION USING FORMULA 2.3 AND 2.4 AND THE FOLLOWING TESTS SCORES: 7, 2, 7, 6, 5, 6, 2
variance
VARIANCE
  • USEFUL STATISTIC IN CERTAIN HIGH LEVEL STATISTICAL PROCEDURES LIKE REGRESSION ANALYSIS AND ANALYSIS OF VARIANCE (ANOVA)
  • CALCULATED BY SQUARING THE STANDARD DEVIATION (S2)
  • STANDARD DEVIATION = S = 4
  • VARIANCE = S2 = 42 = 16