Exercise - Relative Humidity of US Cities

The data set HUMIDIT2 contains relative humidity data for 264 US cities. The data set contains the data for June and September (morning and afternoon). In addition, the annual averages are stored in the last two columns. The data has been published by the National Climatic Data Center on their Web site: http://www.ncdc.noaa.gov/.
 

Check whether there is a significant difference between the means of humidity
 

• in morning and afternoon values (both for June and September)
• in June and September values (both for morning and afternoon readings)
• in September and the annual averages (both for morning and afternoon readings)

Make your decisions on  5% and 1% levels of significance. Is there any difference between those two levels?

You can now go directly to the  DataLab  in order to experiment with the data.