1. Dr. Mona Hassan Ahmed Hassan
Prof. Biostatistics

2. for Diabetes Epidemiology
Computer Utilization
for Diabetes Epidemiology

3. Objectives Statistical Software What to do before sitting to PC?
How to generate and interpret results?
Objectives

4. Data Coding Numbers OR Symbols
Transformation of qualitative information into
Numbers OR
Symbols

5. Data Preparation Ser. Ser. Column Code Age Sex MS Educ. Coding form
Either the information is transferred from the original record to a “coding sheet”
Ser.
Ser. 
Column
Code
Age
Sex MS
Educ.
Coding form

6. Code 1 10/01/2008 25/08/1986 ID 1 1. Date of Interview 10/1/2008 f
160 58
ID 1
1. Date of Interview
10/1/2008
2. What is your date of Birth?
25/8/1986
3. What sex are you?
Male (m) Female (f)
4. What is your marital status?
Single (1) Married (2)
Widowed (3) Divorced (4)
5. What is your height (cm)?160
6. What is your weight (kg)?58

7. Coding by more than one person
Precise instructions should be developed for coders
Coders, must be trained
check for inter-coder reliability

8. Sorting of the questionnaires
1-100

9. Describing the Sample
measures of central tendency and variability. 
The appropriate measure of central tendency and variability will depend upon the variables level of measurement and the shape of the distribution. 

10. Scales of measurement

11. Scales of Measurement Nominal Symbols Assigned Ordinal Rank Order
to Runners
Ordinal Rank Order
of Winners
Interval Performance
Rating on a
0 to 10 Scale
Ratio Time to Finish, in
Seconds
Ali
Samy
Ramy
Finish
3rd place
2nd place
1st place
Finish 3 7 9
15.2
14.1
13.4

12. Scales of Measurement

13. Shapes of Distribution
Mean
Median
Mode
68% within mean+SD
95% within mean+2SD
99% within mean+3SD

14. Right-skewed distribution
Mode Median Mean
If Mean > Median  Positive or right skewness
(long right tail)
It arises when the mean is increased by some unusually high values

15. Left-skewed distribution
Mean Median Mode
If Mean < Median  Negative or left skewness (long left tail).
Negative skewness occurs when the mean is reduced by some extremely low values.

16. Inference Developing and Testing a Hypothesis
differences in frequency distributions of nominal level variables  chi-square
associations or correlations between variables,  bivariate correlations  
differences between groups with respect to the distribution of interval/ratio level data. t-tests

17. The most popular statistical packages1
SAS 2
SPSS 3
STATA 4
Epi Info 5
SUDAAN 6
S-PLUS 7
MedCalc 8
Excel 9
Statistica 10
Minitab
Sample size

18. Using Epitable (Under EpiInfo) to Calculate Sample Size

20. SPSS
Statistical
Sciences
Packages
Social
FOR

21. Creating a Data File in SPSSID
Gender Male Female
Date of Birth
Educational Level (years)
Employment Category 1 Clerical 2 Custodial 3 Manager
Current Salary $
Beginning Salary $
Months since Hire
Previous Experience (months)
Minority Classification 0 No 1 Yes

22. Data Entry
Excel
Access
Word
Any Statistical software

23. Data entry

24. Data cleaning General data check: Printout
Quick data check (Frequency tables)
1- Wild codes check (invalid codes)
2- Completeness check: ensure that
all cases collected are
represented in the data file
without replication

25. Simple frequency Data check

26. Perform Descriptive Statistics

27. Descriptive

29. Conduct Simple Correlations and regression

30. Correlation

31. Regression

32. Scatter

33. t- test (Two independent groups)

34. t- test (Two independent groups)

35. t- test (Two independent groups)

36. Paired t- test (Dependent groups)

37. Chi-Square test

38. Thank You