Population VS Sample ◦ Population is a group of all things that share a set of characteristics. ◦ Population parameter – the value that would be obtained if the entire population were actually studied.
◦ Sample is a subset of population that is intended to represent the population. ◦ Sample statistic – the value obtained from the sample. It is used to estimate the population parameter value.
Pharmaceutical Biostatistics: Descriptive Statistics
Population VS Sample cont. ◦ A set of data is a sample from our population. The sample is a subset of the population. ◦ Statistical inference – the process that we used to draw conclusions from a data. ◦ Inference involves using statistics we calculate from the sample to make and informed guess about population. ◦ When we do statistical inference we are interested in drawing conclusions from a set of data (sample) so that we can estimate population parameters.
Pharmaceutical Biostatistics: Descriptive Statistics
We want to know about these‌ We have these to work with
RANDOM SELECTION
sample
population
INFERENCE
​ â &#x; đ?‘‹ (sample mean)
Îź (population mean)
Sample statistic
Population parameter Pharmaceutical Biostatistics: Descriptive Statistics
Population vs Sample cont.
Pharmaceutical Biostatistics: Descriptive Statistics
Population vs Sample cont. #
Example (task)
Population
Sample
1
Characterisation of the weights of tablets in a particular batch
All tablets that constitute the batch
100 tablets selected for weighing
2
Evaluation of the IQ of school All school children in Selangor in year 1 children in Selangor in year 1
100 children in year 1 attending selected schools in Selangor
3
Evaluation of the worldwide incidence of head injury in professional boxers
Examination of the medical records of all professional boxers in the UK
All professional boxers worldwide
Pharmaceutical Biostatistics: Descriptive Statistics