1. Statistics
Statistics is that field of science concerned with the collection, organization, presentation, and summarization of data, and the drawing of inferences about whole body of data when only a small part of the data is observed or examined.

2. Biostatistics:
Is that field of statistics in which the data being analyzed were derived from the biological sciences and medicine.

3. Uses of statistics:

4. Data:
The raw material of statistics
Value:
It is the numerical representative of the measurement of the variable.

5. Sources of data:

6. Variables are one of two types 1-Quantitative variable
Any characteristic that can take different values in different occasions, places, persons, and time. e.g. Height, weight, age, etc...
Variables are one of two types
1-Quantitative variable
2-Qualitative variable (categorical)

7. There is another classification of variables according to;
There is another classification of variables according to;
1-Nominal scale:
2-Ordinal scale:
3-Intervale scale:
4-Ratio scale:

8. Population:

9. Sample:

10. Sampling

11. Reasons for sampling:

12. 1-non-probability sampling (non-random sampling) .

13. 2-probability sampling (random sampling):  

14. Random sampling:

15. There are different methods of random sampling;
A-Simple random sampling:
B-Systematic random sampling
C-Stratified random sampling
D-Multistage random sampling
E-Cluster random sampling

16. Sampling error

17. The causes of sampling error due to samples variation:

18. The causes of sampling error not due to samples variation:

19. Standardization:

20. Reproducibility:

21. Calibration:

22. Calibration: Intra-examiner: one examiner
Inter examiner: more than one examiner