There are several factors that are important in monitoring global or U.S. temperature: quality of raw observations, length of record of observations, and the analysis methods used to transform raw data into reliable climate data records by removing existing biases from the data. (ncdc.noaa.gov)
All the curves have been centered to have the same mean and standard deviation over the length of record, so as to make them more comparable. (realclimate.org)
If the text expands, so might the length of the recording, which might make the voiceover talent have to speak faster. (elearningindustry.com)