Analyzing Time Trends

You can compare metrics month over month or year over year to analyze time trends.

When requesting metrics with the StreetLight Advanced Traffic Counts API, you can specify a series of months or years for which you want metrics. This allows you to compare metrics over the series of months ("month-over-month") or years ("year-over-year"), and analyze changes over time.

You can analyze month-over-month or year-over-year time trends by defining a contiguous range with the date_range parameter in the Get metrics for a geometry endpoint.

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Use date_range for contiguous months or years. Use date_ranges only for disjoint ranges with agps. Use date for a single month or year. Include year_month in fields when the response spans multiple periods.

Month-over-month time trends

For example, the following date_range in the Get metrics for a geometry endpoint would get metrics for October through December 2021:

"date_range": {
    "start": {"month": 10, "year": 2021},
    "end": {"month": 12,"year": 2021}
  },

Year-over-year time trends

If you only define a year for the start and end of the date range without specifying a month, you will get metrics for each year in the range. The following date_range would get metrics for 2020 through 2022:

"date_range": {
    "start": {"year": 2020},
    "end": {"year": 2022}
  },

Time trends from 2024 - 2025

With the agps source, you define an OSM vintage along with your geometry. If your date range includes months across 2024 and 2025, specifying both available OSM vintages is recommended. For example, the metrics call would include the following parameters:

"date_range": {
    "start": {"month": 10, "year": 2024},
    "end": {"month": 3,"year": 2025}
},
"osm_vintage": [202501, 202302],

This ensures that metrics are paired with the correct geometry for the year in which the data occurred. For more information, [Defining Geometry].