Biostatistics is a branch of statistics that emphasizes the statistical applications in the biomedical and health sciences.  

Steps in scientific investigations 

• Formulation of the research problem 
• Identification of key variables 
• Statistical design of an experiment 
• Collection of data 
• Statistical analysis of the data 
• Interpretation of the analytical results 

The Levels of Measurements 

• Nominal 
• Ordinal 
• Interval 
• Ratio 

A nominal measurement scale represents the simplest type of data, in which the values are in unordered categories. 

• Examples: 
• Gender (F, M) 
• Blood type (type A, type B, type AB, type O) 
• Yes/no response on a survey questionnaire 

In the ordinal measurement scale, the categories can be ordered or ranked. 

•  The amount of the difference between any two categories, though they can be ordered, is not quantified. 

Examples: Loe-Silness gingival index, Tooth mobility, Pulp status - (normal, mildly necrotic, moderately necrotic, severely necrotic) 

In the interval measurement scale observations can be ordered, and precise differences between units of measure exist. 

However, there is no meaningful absolute zero. 

Examples: IQ score representing the level of intelligence, Temperature - A thermometer might have intervals of degrees. 

The ratio measurement scale possesses the same properties of the interval scale, and there exists a true zero. 

•  Examples: Weight in pounds, Patient’s waiting time in a dental office 

Methods of Collecting Primary Data 

• Observation method 
• Through questionnaires 
• Interview method 
• Through schedules 

Observation method 

• Observation becomes a scientific tool when it serves a formulated research purpose, is systematically planned and recorded and is subjected to checks and controls on validity and reliability. 
• Information is sought by way of investigator’s own direct observation without asking from the respondent. 

Interview Method 

• The interview method of collecting data involves presentation of oral-verbal stimuli and reply in terms of oral-verbal responses. 
• Personal interview method requires a person known as the interviewer asking questions generally in a face-to-face contact to the other person or persons
• Telephonic method is collecting information through contacting respondents on telephone.  

Pilot survey 

• Pilot survey is the replica and rehearsal of the main survey. 

Selection of Appropriate Method for  Data Collection 

• Nature, scope and object of enquiry 
• Availability of funds 
• Time factor 
• Precision required 

 Article by Dr. Siri P. B.