Frequently Asked Questions

- For more help using Joinpoint check the Surveillance Research Program Web site for Joinpoint: Frequently Asked Questions.

Citation & References

1. Is there a suggested citation for Joinpoint?

2. Are there any reference papers that can help me understand the methodology?


Software Updates and Installation

3. What are the most recent changes to the Joinpoint program?

4. How can I replicate previous results with a newer version of Joinpoint?

5. Can Joinpoint run on a Macintosh PC?


Model Estimation and Selection Methods

6. Why doesn't the Joinpoint program give me the best possible fit? I can see other models with more joinpoints that would fit better. Exactly how does the program decide which tests to perform and which joinpoint model is the final model?

7. Describe the permutation test used here.

a. How many permuted data sets should I use?
b. What does the p-value mean for Joinpoint?
c. Why are new significance levels being used in Version 3.0 and succeeding releases?

8. What is the Bayesian Information Criterion method for selecting the best model?

9. Why should I use the Permutation Test (PT) when Bayesian Information Criterion (BIC) is so much faster?

10. Should I use the linear or log-linear model?

11. When running the test for pairwise differences with the Coincident option, should I use a weighted or unweighted model?

12. Does the test of parallelism of two series require the series to be uncorrelated?

13. For a statistical test of parallelism between two groups, how is the assumed number of joinpoints (which is displayed on the comparison tab) determined?

14. Can the Joinpoint software estimate the autocorrelation parameter?

15. Why did the default settings for Grid Search change?

16. Why is the Hudson's method disabled?

17. What is Tau?

18. Why would I choose Data Dependent Selection as a Model Selection Method?

19. What happened to the Clustering controls on the Advanced Analysis Tools Tab?

20. Why does the number of joinpoints for the best fit sometimes decrease when the maximum number of joinpoints is increased?



21. What is an APC?

22. What is an AAPC?

23. How is the AAPC Computed?

24. Can we compare AAPCs for two independent groups?

25. What are the relative advantages and disadvantages of reporting an AAPC over APCs?

26. What is the advantage of reporting an AAPC over an APC computed by fitting a single line (on a log scale) to the data?

27. Which Method is better to use for the Empirical Quantile CI calculations?

28. Why is the Empirical Quantile Confidence Interval option labeled as "Alpha"?

29. When I fit a Joinpoint model to find the rate trend, why doesn't the APC for one of the segments match the APC found by SEER*Stat for the corresponding segment?

30. Sometimes, the APC for one segment is significantly different from zero, but when an extra joinpoint in the segment is determined by the Joinpoint software, neither APCs for the two consecutive segments are significant. Why?


Applications of Joinpoint

31. I used the program on SEER data and do not get the same answers as in the SEER Cancer Statistics Review. Why?

32. Sometimes, the change in the slopes between two segments is not statistically significant (p- value>0.05) from the t-test, but there is joinpoint between two segments or vice versa. Why?

33. Can I do Joinpoint regressions where the time intervals are not equally spaced or the time points are not integer?

34. Can Joinpoint be used to model proportions or percents?

35. How does the Joinpoint software deal with zeros in the dependent variable?

36. Can I use Joinpoint to project or extrapolate into the future?

37. What type of SEER*Stat sessions are compatible?

38. How do you handle an independent variable that is not yearly data, but is continuous data and is presented in discrete categories, or is ordinal data?


Using Joinpoint Results

39. How do I import Joinpoint's graphs into other software such as Word, Excel, or PowerPoint?

40. How do I print Joinpoint results?

41. How do I save Joinpoint results to PDF or Word?

42. How do I export Joinpoint results to a text file or to Excel?

43. How do I export high resolution graphs?


Data Sources

44. When I use Excel as my data source, why do I get "####" in the data?