سابقه و هدف: آب هوای یک منطقه در دوره بلندمدت را اقلیم گویند. شناسایی طبقه‌بندی اقلیمی از دیرباز مورد توجه متخصصان هواشناسی بوده است. محققان با به کارگیری روش ­های مختلف استفاده متغیرهای همچون بارش دما، زمین مناطق همگن طبقه ­بندی کرده‌اند نتایج پهنه‌بندی ارزیابی کمبود منابع مقیاس­ های کوچک بزرگ منظور پیش‌بینی اقدامات عملی برای کنترل خشکی آسیب‌پذیر به‌کار برده‌اند. هدف این تحقیق به‌‌روزرسانی تحل...

Earnings are riskier and more unequal for households born in the 1960s 1980s than those 1940s. Despite improvements financial conditions, younger generations less likely to be living their own homes older at same age. By using a life-cycle model with housing portfolio choice that includes flexible earnings risk aggregate asset price risk, I show changes dynamics account large part of reduction ...

This paper builds a new microdatabase that covers 100 countries at all income levels and long-run time series in the United States (1870–2010) Mexico ( 1960–2010) to document how modern tax system arises over development. I establish set of stylized facts, which show exemption threshold decreases distribution as country develops, tracking growth employee share employment occurs gradually furthe...

Immigrants can expand labor supply and compete for jobs with native-born workers. But immigrants may also start new firms, expanding demand. This paper uses US administrative data other sources to study the role of in entrepreneurship. We ask how often companies, many these firms create, founded by individuals compare. A simple model provides a measurement framework addressing dual roles as fou...

abstract research and development (r&d;) spending plays a major role in innovation, raising productivity and increasing economic growth. the purpose of this paper is to investigate the impact of r&d; spending on growth and total factor productivity (tfp) in iran's agricultural sector. we estimate growth and productivity models using auto-regressive distributed lag (ardl) approach and data over ...

Population aging is expected to slow US economic growth. We use variation in the predetermined component of population across states estimate impact on growth GDP per capita for 1980–2010. find that each 10 percent increase fraction age 60+ decreased by 5.5 percent. One-third reduction arose from slower employment growth; two-thirds due labor productivity Labor compensation and wages also decli...