Monday, November 12, 2007
Thursday, November 8, 2007
Statistics - Percentile Rankings
P.R. are used to compare individual scores to groupe scores. It is called this because a single value is calculated in relation to all there values..
P.R. = (B + 0.5E) . 100
--------------
n
B = the number of scores below the given score
E = the number of scores equal to a given score ( if there are no other scores equal to use 0)
n= the total number of scores
Measures of Variability - Standard Deviation
Range = the diffrence between the largest and the smallest
Standard Deviation = a measure of variability
To calculate the standard deviation of a groupe of numbers it can be determined by using these steps
1. Calculate the mean of the numbers.
2. Determine the diffrence between each number
3. Determine the squares of the differences
4. Determine the sum of these squares
5. Divide the sum of the squares by n -1
6. Calculate the square root of this number
Normal Distributions
Characteristics of the normal curve :
1. Bell Shaped - infanite in both directions
2.Symetric about the mean
3. median
4. is appromiatly all of the data
Correlation Coefficient
Correlation Coefficiant = how to interpret a number that measures a relationship between two sets of values.
Positive Correlation = means that as one variable increases another variable also increases
-1 <> 1
- -
( the range of values for all correlation coefficiants is always between the above)
P.R. are used to compare individual scores to groupe scores. It is called this because a single value is calculated in relation to all there values..
P.R. = (B + 0.5E) . 100
--------------
n
B = the number of scores below the given score
E = the number of scores equal to a given score ( if there are no other scores equal to use 0)
n= the total number of scores
Measures of Variability - Standard Deviation
Range = the diffrence between the largest and the smallest
Standard Deviation = a measure of variability
To calculate the standard deviation of a groupe of numbers it can be determined by using these steps
1. Calculate the mean of the numbers.
2. Determine the diffrence between each number
3. Determine the squares of the differences
4. Determine the sum of these squares
5. Divide the sum of the squares by n -1
6. Calculate the square root of this number
Normal Distributions
Characteristics of the normal curve :
1. Bell Shaped - infanite in both directions
2.Symetric about the mean
3. median
4. is appromiatly all of the data
Correlation Coefficient
Correlation Coefficiant = how to interpret a number that measures a relationship between two sets of values.
Positive Correlation = means that as one variable increases another variable also increases
-1 <> 1
- -
( the range of values for all correlation coefficiants is always between the above)
Test on monday.I found a standard Deviation calculator at http://invsee.asu.edu/srinivas/stdev.html it works really good for checking you answers.
Wednesday, November 7, 2007
correlation coeficients
Mental math, followed by corrections of correlation coefficient questions 1-4, quiz monday on stats, Question of the day: Is the use of computers too distracting for working in the classroom?
Tuesday, November 6, 2007
Lesson 3 Corrections and Lesson 4
We also did a Mental Math at the start of the class. There is also a quiz on Thursday on Statistics.
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