Understanding the data

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Sourcing Google Trends data

This lesson has been adapted from Google News Lab and is reproduced with permission.

In this lesson, you will learn:

  • How to interpret the graphs and data in Google Trends results

Google Trends analyses a percentage of Google web searches to determine how many searches were done over a certain period of time.

For example, if you’re doing a story about mosquito-born diseases, and you want to see if there was a recent uptick in searches about the zika virus, select “Past 90 days”. Trends analyses a percentage of all searches for “zika virus” within those parameters.


Reading the Interest Over Time graph

When you search for a term on Trends, you’ll see a graph showing the term’s popularity over time in (nearly) realtime. Hovering your mouse over the graph reveals a number, which reflects how many searches have been done for the particular term relative to the total number of searches done on Google.

Numbers on the graph don’t represent absolute search volume numbers because the data is normalised and presented on a scale from 0-100, where each point on the graph is divided by the highest point, or 100. The numbers next to the search terms at the top of the graph are summaries or totals.

A line trending downward means that a search term’s relative popularity is decreasing—not necessarily that the total number of searches for that term is decreasing, but that its popularity compared to other searches is shrinking. In other words, even if the graph is moving downwards the number of searches for “zika virus” may be actually be increasing but not as quickly as other terms of interest.

Finding the most searched topic in every region or country

When you search for multiple terms on Trends, you’ll see a comparative map showing which term or topic is most searched in each region.

Let’s compare the search terms “zika virus” and “malaria.” You’ll find that over time, malaria has experienced a steady query rate, while zika was barely searched for until a huge spike in January 2016.

Comparing by region

Looking at search interest by region shows that zika virus was more searched in the US and Brazil but malaria was still a more popular search topic in Africa and Asia.

Look at the map colouring below (red is malaria).

Rising data

At the bottom of your results page is the Related Searches chart, which can be used to determine the top and rising terms associated with any topic or trending story.

On the chart, the Rising tab represents terms that were searched for with the term you entered (or overall, if no search term was entered) which had the most significant growth in volume in the requested time period. For each rising search term, you’ll see a percentage of the term’s growth compared to the previous time period. If you see “Breakout” instead of a percentage, it means that the search term grew by more than 5,000%.

The percentages are based on the percent increase in search interest for the selected time frame. If we’re looking at the last seven days, the benchmark for the rise in searches for the term “zika virus” would be 7 days prior; if it was the last 30 days, the benchmark would be for the 30 days prior. The only exception is when viewing the full history (2004-Present) when the percentages are benchmarked at 2004.

Reading the Related searches chart

Click the dropdown to see Top terms. This table shows terms that are most frequently searched with the term you entered, in the same search session, with the same chosen category, country or region. If you didn’t choose a search term (and just chose a category or region), overall searches are displayed.

Data that is excluded from Trends

Trends excludes certain data from your searches:

  • Searches made by very few people Trends only analyses data for popular terms, so search terms with low volume appear as 0 for a given time period.
  • Duplicate Searches Trends eliminates repeated searches from the same user over a short period of time for better overall accuracy.
  • Special characters Trends filters out queries with apostrophes and other special characters.

Let’s review!

Let's Review: Trends 2