MS 150 Statistic Quiz 3 Spring 2005 • Name:

Until recently the only way to connect to the Internet from the home was by using a dial-up modem. During the past past five years home users have had new choices that offer higher speed, faster Internet connections from their home including cable modems, Digital Subscriber Lines, and direct satellite links. Dial-up modems are seeing decreasing usage with each year. Forecasts for the dial-up modem market are all negative. The table below shows the year and the usage or projected usage of dial-up modems. The modem numbers are in millions of households using modems.

1. _______ Calculate the slope of the linear regression for the data.
2. _______ Calculate the y-intercept of the linear regression.
3. _______ Is the correlation positive or negative?
4. _______ What is the projected number of households which will be using modems in 07?²
5. _______ What is the projected year in which 20 million households are likely to still be using modems?²
6. _______ Calculate the Karl Pearson product-moment correlation coefficient r for the data.
7. _______ Is the correlation none, low, moderate, strong (high), or perfect?
8. _______ What is the predicted year in which zero households are likely to still be using modems?²

¹ eWeek, 23 August 2004 quoting data from Veronis Salter Stevenson, PO Media, Federal Communications Commission, National Cable and Telecommunications Association, DSL Forum, Telecommunications Industry Association, and Kagan World Media. Data reverse engineered from chart by instructor.

² Although predicting or projecting beyond the end of the underlying data typically introduces large uncertainties and may result in meaningless results, for the purposes of this quiz make these calculations as if the relation holds for these points beyond the end of the data.