Some Statistical Terms

Mean   =

S   Observations Number of Observations

 

• Median = the middle number in a series of numbers.
• Mode = the most frequently repeated number.
• Average median = Median – Mode

• Variance (S2)   =

  S   (X – X)2 n – 1

  Binomial: when the mean is equal to the median & mode, this is called normal distribution.

 

Standard Deviation (SD)   =

S   (X – X)2 n – 1

Standard Error of the Mean    (SEM) = (Standard Deviation of the Mean)

SD n

Coefficient of Variance   = (Relative SD or Precision)

SD X

X 100

 

• The Error is smaller than the standard (average) deviation.
• When the standard deviation is 95% the error is + 2%.
• If a normal population is 99%, the average deviation is + 3%
• If a normal population is 95%, the average deviation is + 2%
• If a normal population is 68%, the average deviation is + 1%
• Type I error: is a false positive result.
• LD50 (Lethal dose 50) is the dose that kills 50% of experimental animals.
  • Mean half-life = 3 + 9 + 5 + 6 + 4 / 5 = 27 / 5 = 5.4 hr. 
  • Median is =  3  4  5  6  9  =  5  ( arrange & select the middle number)

 

1. 5 subjects given a single IV dose of a drug have the following elimination half-lives : 3,9,5,6, & 4 hrs. Calculate the mean half-life & the median

1. What is the acceptable rate of Rx turn-over:

1. 0.5%                                              c.   15%
2. 2.5%                                              d.   5%
3. Abnormal                                      c.   Normal
4. Binomial
   1. Eliminate error I                   b.   See the involvement of error II

1. When mean, median and mode are equal, distribution is said to be:

1. In clinical trials a large population size is included to:

1. Which is not included in statistical data:
   1. Rejected data                         b.   Control group data
2. Which is not included in statistical data:
   1. Range                                     c.   SD
   2. Coefficient of variance
3. Type II error is (false negative)
   1. two drugs are show no different but actually different is present