But only indirect measurements have been made, by taking air samples from storm clouds.

Previous studies, which made indirect measurements, had concluded that only 1 in every 10,000 to 100,000 of the T4 cells was infected.

Kenya's Planning Ministry says the growth rate is 3.7 percent, a figure based on indirect measurements taken since the last census.

These signals give an indirect measurement of the speed of wind near the water in clear or cloudy weather.

In contrast, general advertising uses indirect measurements, such as awareness or engagement, since there is no direct response from a consumer.

The Industrial Revolution introduced wide scale use of indirect measurement.

This is indirect measurement that depends on calibration to read pressure or vacuum correctly.

An exposure analyst can use direct or indirect measurements to determine if a person has been in contact with a specific contaminant.

However, both studies used indirect measurements of Lp(a), which some experts say can lead to spurious results.

Due to the subjectivity and labor involved with the first method, indirect non-contact measurements are typically preferred.