Our Frequently Asked Questions are divided into the following categories:

• Concepts
• X-12-ARIMA
• SEATS
• Diagnostics
• Trouble-Shooting

Do you have questions not answered here?

Please email our information desk at info@catherinechhood.net
or suggest new questions for the FAQ at faq@catherinechhood.net.

FAQ (and Glossary)

1. What is a time series?
2. What is seasonal adjustment?
3. What kind of data do we need for seasonal adjustment?
4. Why seasonally adjust data?
5. How much data do I need to get a reasonable adjustment?
6. What are the components of a time series decomposition?
7. What effects are removed during seasonal adjustment?
8. What is a regARIMA model?
9. How do I generate a seasonally adjusted series?
10. What are seasonal filters?
11. What are trend filters?
12. Why do the seasonal factors change when new data is added?
13. How do I choose between an additive or a multiplicative model?
14. What is an indirect (or a direct) adjustment? Why would I need one?

1. What is X-12-ARIMA?
2. How do I get a copy of X-12-ARIMA?
3. How do I run X-12-ARIMA?
4. How do I find what I need from the output file?
5. How does X-12-ARIMA estimate the trend and seasonal components?
6. How does X-12-ARIMA estimate the trading day and moving holiday components?
7. What seasonal filters are available in X-12-ARIMA?
8. What trend filters are available in X-12-ARIMA?
9. How does X-12-ARIMA handle extreme values or outliers?
10. What if I have a holiday not included in X-12-ARIMA?
11. How do I process a large number of series?
12. How do I get X-12-ARIMA to calculate an adjustment for the total of my series?
13. How do I get updates and/or more information on X-12-ARIMA?
14. Is there training available?
15. How do I get started? How do I write all the input files I need? How do I find out about the diagnostics?
16. Can I run X-12-ARIMA from Excel?
17. When will X-13 be available and what will it be like?
18. More questions?

1. What is TRAMO/SEATS?
2. How do I get a copy of TRAMO/SEATS?
3. More questions?

1. What are the features of a quality seasonal adjustment?
2. What diagnostics are available in X-12-ARIMA to help us judge the quality of the adjustment?
3. What do I do if the diagnostics fail?
4. How much data do I need to get diagnostics information from X-12-ARIMA?

1. What do I do if I can't get X-12-ARIMA to run?
2. What do I do if I click on a spec file and I get an error about Microsoft PKCS #7 Certificates files?