Global warming, Part II

Global warming, Part II#

Let’s consider a limited set of climate data, examining temperature differences in 1948 vs 2018. We sampled 199 locations from the National Oceanic and Atmospheric Administration’s (NOAA) historical data, where the data was available for both years of interest. We considered the change in the number of days exceeding 90°F from 1948 and 2018 at 199 randomly sampled locations from the NOAA database. The mean and standard deviation of the reported differences are 2.9 days and 15.9 days.

Part 1#

Calculate the lower bound of a 88% confidence interval for the average difference between number of days exceeding 90°F between 1948 and 2018. We’ve already checked the conditions for you.

Answer Section#

Please enter a numeric value in.

Part 2#

Calculate the upper bound of a 88% confidence interval for the average difference between number of days exceeding 90°F between 1948 and 2018. We’ve already checked the conditions for you.

Answer Section#

Please enter a numeric value in.

Part 3#

Interpret the interval in context.

Answer Section#

  • We are 88% confident that there was an increase of [lower bound] to [upper bound] in the average number of days that hit 90°F in 2018 relative to 1948 for NOAA stations.

  • There is a 88% probability that the true average difference in the number of days exceeding 90°F between 1948 and 2018 lies between [lower bound] and [upper bound].

  • There is a 88% probability that the number of days exceeding 90°F will be between [lower bound] and [upper bound] days higher in 2018 compared to 1948 for all locations.

  • There is a 88% probability that the observed average difference of days exceeding 90°F between 1948 and 2018 is exactly between [lower bound] and [upper bound] days.

Part 4#

Does the confidence interval provide convincing evidence that there were more days exceeding 90°F in 2018 than in 1948 at NOAA stations? Explain.

Answer Section#

  • Yes, since the interval lies entirely above 0.

  • No, since the interval is not entirely lying above 0.

Attribution#

Problem is from the OpenIntro Statistics textbook, licensed under the CC-BY 4.0 license.
Image representing the Creative Commons 4.0 BY license.