1. Data Transformation, T-Tools and Alternatives
Lab 1 Instruction
Data Transformation, T-Tools
and Alternatives

2. Topics 1. Describing and Displaying Data 2. Data Transformations
3. Tests for Differences between
Two Independent Samples / Two Paired Samples

3. 1.Displaying and Describing Data
3 principal procedures for describing and exploring continuous data:
Analyze  Descriptive statistics 
Frequencies
Descriptives
Explore

4. Frequencies procedure

5. Descriptives procedure

6. Explore Procedure
The Explore procedure in SPSS allows you to obtain descriptive statistics for your data, identify extreme observations, calculate the percentiles of the distribution, and display the data with a variety of plots.

7. Explore Procedure

8. Explore Procedure

9. Explore Procedure

10. Boxplots
Single group

11. Boxplot
More than one groups (use labels)

12. Boxplot

13. Normality Plots – Q-Q Plots

15. Describe the data Center: mean; median Spread: s.d.; IQR=Q3-Q1
Shape: symmetric VS skewed (left/right)
Outliers: <Q1-1.5*IQR or >Q3+1.5*IQR
Normality according to boxplot/QQ plot/Kolmogorov-Smirnov test

16. 2. Data Transformations
Compute Variables e.g. Natural Logarithm Transform

17. Natural Logarithm Transformation

18. Other Useful Data Transformations
The type depends on the form of the distribution of the variable on the original scale.
Some recommended data transformations :

19. 3. Tests for Differences between Two Paired Samples
used for paired (matched) data
Paired-Samples T Test

20. Read output

21. 4. Tests for Differences between Two Independent Samples
Independent-Samples T-Test

22. Assume Equal variances or not?! ---- refer to Levene’s test result

23. Tips for the assignment Generally~ Read the question carefully
Tips for the assignment Generally~ Read the question carefully. Follow the marking schema

24. Q4 & Q8 b
Null hypothesis, Alternative hypothesis;
value of the Test statistic; p-value;
Conclusion; (maybe) Confidence interval.
Q8 a&c
“the differences in LLSIR on the log scale between normal and hypoplastic lungs” VS
“the ratio of mean LLSIR of normal lungs to that of hypoplastic lungs”
use antilogrithm, see Page 16 in the instruction