Oil is the primary source of income in the Libyan economy; hence, it is important to more fully understand the economic factors associated with this sector of the economy. We applied a recent growth theory model to develop a better understanding of the relationship among capital, labor, domestic consumption of oil, oil exports and gross domestic product (GDP) in the Libyan economy. A log linear model was estimated using annual data for the period 1980 to 2012. All of the coefficients were significant at the 0.05 level except the log of labor, which was significant at the 0.0613 level. The signs associated with the variables were consistent with economic theory. The adjusted R square was 0.912 indicating that approximately 91 percent of variation in GDP was explained by the independent variables. There was only limited multicollinearity in the model as all Variance Inflation Factors (VIF) values were less than 10. Breusch Pagan and Anderson-Darling test results indicated a constant variance and that the errors were normally distributed, respectively. Similarly, the Durbin-Watson statistic indicated an absence of autocorrelation at the 0.05 level. The resulting elasticities were positive and strongly inelastic, indicating that large changes in each of the variables would be required to dramatically increase GDP. Nevertheless, it is clear that oil will continue to play a leading future economic growth and development.

This study aims to know the time between apple production and marketing to help decision makers for apple products at Washington, in the USA. In order to do so, it needs an application of OLS for a linear and non- linear model for diameter apples and length apple over the years 2010-2013. The diameter or size apple linear model includes DAFB, FB, latitude, mean80, years, and FB. The results indicated that all independent variables are significant and Adj R-squared explains about 75 percent of diameter apple. While the length apple linear model includes DAFB, years, FB, longitude, elevation, latitude, mean120, and mean70.The resulted sate that all independent variables are significant and Adj-R-squares illuminates about 84percent of size apple. Moreover, Actual value and predicted values for linear and nonlinear models are very close. Thus, those models can help farmers make a good decision for apple industry, and achieve to get best size and length for their apple crop.

There is a strong need to study sustainability and depletion accounting of oil in the Libyan economy because oil production and export is the single largest source of national income in the country. This study covers the time period from 1990 to 2009. Throughout this period, the Libyan national economy used its oil and petroleum industries to increase national income. Development sustainability can be defined as investment divided by GDP. This measure provides an indication of the low level of sustainable development in Libya over the period of analysis, which is 0.38 on average. It is important that the Libyan government develop and implement plans and strategies for achieving sustainability and the maintenance of oil resources.Carbon dioxide emissions provide another indication of the presence or absence of sustainability. The ratio of carbon dioxide ranged from a minimum of 8.50 metric tons per capita in 1990 to 10.00 metric tons per capita in 2009 and average 9.07 metric tons per capita over the course of the study period. CO2 emissions were also much higher than other countries in the Middle East and North Africa. This suggests there was relatively little interest in the sustainable development of the Libyan economy during this period. The Environment Domestic Product (EDP) increased sharply from the beginning of the study at $24.23 billion in 1991 to $45.87 billion in 2009 in constant dollars. Again, one can infer that policy makers did not consider the depletion of oil resources and the environment in their planning process, or at least did not place a high level of concern on this issue.