Data collected over time (e.g. quarters, weeks, or some other ordinal information). For example:
How do you enable comparing to the previous period?
You can enable this feature by going to either the Table or Project options via
- Edit > Table Options
- Edit > Project Options > Customize.
- Within the Table/Project Options click the Statistical Assumptions tab. On the bottom left is a drop-down menu for Date questions, where you can set it to compare to previous period.
Whether this setting is on or off, it will be clarified in the footer of the table by default when you use a Date Question. It will either say “Significance Testing: Compare to previous period” or “Significance Testing: Compare to rest of data”.
How do you turn a categorical variable into a Date question?
if (wave == 1) Q.EncodeDate(2018,01,31);
else if (wave == 2) Q.EncodeDate(2018,02,28);
else if (wave == 3) Q.EncodeDate(2018,03,31);
else if (wave == 4) Q.EncodeDate(2018,04,30);
You now have a new numeric variable in your Variables and Questions tab. Change the variable type to “Date/Time” and you’ll now have a new Date/Time question. Be sure to check the Values to set your desired aggregation.
This Date/Time question will now be available for you to use in your cross-tabs. And, pertinently, for use with the statistical testing against a previous period!
How to Create a Time Series Graph
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