Which type of tax is imposed on specific goods and services at the time of purchase?

Which of the following works like a credit card with the time clock?

a. Biometric time clocks b. Magnetic swipe ID cards c. Mobile remote devices d. Proximity cards

The measures of accuracy of the forecasts:

a. check how well a particular forecasting method is able to reproduce the time series data that are already available. b. use the current value to estimate how well the model generates previous values correctly. c. predict the future values and wait for a pre-defined time period to examine how accurate the predictions were. d. check to see if the forecast error is negative.