Biostatistics

 Biostatistics

Branch of statics applied to biological or medical sciences. 

Or

It is branch of statics that deals with that are relating to living organisms. 

Steps  :

• Generation of hypothesis 
• Collection of data 
• Statistical analysis 
• Application of statistical principles

Biostatics comprises set of principles and methods for generating and using quantitative evidence to address scientific questions. 

Applications of Biostatistics :

• Use to study normal and healthy population and to establish limits for abnormality. 
• In anatomy and physiology use to study mean, pulse rate, mean and volume of height, weight and their correlation in healthy persons. 
• Comparing the action of different drugs or dosage forms. 
• Used to access the relative potency of drugs and to compare the efficacy of important drugs.
• In community medicine and public health statistics use to find the usefulness of SERA and VACCINES. 
• Used for comparison of vaccinated and un- vaccinated death and to find whether the difference is observed is statistically significant.
• Statistics used for epidemiological studies to find the role of caustitive factors. 
• Statistical tool are used to detection of reasons for reduction of birth rate.

Frequency distribution :

Repeatation of observation is called frequency. 

A systemic presentation of different values taken by the variables together with corresponding frequencies is called frequency distribution. 

Types:

• Grouped frequency distribution 
• Ungrouped frequency distribution

Characteristics of frequency distribution :

• Measure of central tendency and location. 
• Measure of dispersion 
• Measure of data by extent of system.
• Measure of central tendency or central point or typical value of data set. 

Mean:

A single figure gives complete features of the phenomenon and to represent whole data. 

Types:

• Geometrical mean : set of n observations is defined as the nth root of their product. 
• Harmonic mean : it is defined as reciprocal of the arithmetic mean of reciprocals of given items. 

Advantages of mean :

1. Simple to calculate and understand. 
2. Sum value is always determined it is never indefinite. 
3. It can be used in other algebraic calculations no need of sorting or arrangement. 
4. It is stable and not affected by variation of sample. 

Disadvantages of mean : 

1. Mean is greatly affected by the extreme values. 
2. Sometimes mean may provide confusing impressions. 
3. The mean cannot be predicted by just inspecting the sample item. 
4. If a single value is missing mean cannot be calculated. 
5. In case of opened end classes mean cannot be calculated. 
6. Graphical representation of mean is not possible. 

Applications of mean : 

• Arithmetic mean use to measure the standard deviation. 
• Arithmetic mean used in the construction of indexed number. 
• It is used in hypothesis testing. 

Median : 

It is a positional average defines as the size of the item which lies at the center when all items or arranged in either ascending or descending order. 

For example in the data set 1,3,3,6,7,8,9 the median is 6 the fourth largest and also the fourth smallest number in the sample. For continuous probability distribution the median is the value such that a number is equally likely to fall above or below. 

Mode :

The mode of a set of data values is that appears most often. It is the value of x at which its probability mass function takes its maximum value. In other words, it is the value that is most likely to be sampled. 

It is a value in a series which occurs with in the highest frequency.