Last month the National Federation of Independent Business (NFIB) reported the sixth consecutive monthly rise in its optimism index, making it a good time to look at what the optimism is about. Job growth, expansion of the service sector, more companies increasing stocks and fewer reducing them, all come into the mix.

Government figures in early March put job growth for February at over 200,000 - the third month in a row which has seen such a strong performance.  Along with this, unemployment is holding steady at 8.3%, the lowest figure for three years. Long-term unemployment, however, remains a big challenge.

Signs that the market believes there are real reasons for optimism are good. Wall Street is reacting well and Treasury debt prices have dropped, with dealers lessening their belief in the need for further bond buying by the US central bank.

The percentage of Americans in work or actively looking for work has risen slightly with the workforce increasing by 476,000. This is the biggest increase in the workforce since April 2010.

That we can really only think in terms of optimism rather than hard evidence is shown by the fact that economic growth is still expected to slow from Q4 2011's 3%. High fuel prices and recession in Europe are thought to be the main reasons for three flat months in consumer spending. This is exacerbated by the fact that wage increases continue to lag behind inflation.

All of February's job increases came in private firms. A very interesting aspect being that 31,000 workers were taken on in manufacturing all of which were in firms making long-lasting goods. There is an obvious message here in terms of what the consumer market is looking for and prepared to invest in.

The service sector is responsible for two-thirds of US economic activity so a rise in the Institute for Supply Management services index is always good news. Economists expected it to drop in February, instead it rose from 56.8 to 57.3. This is the highest it has been since February 2011. A figure above 50 indicates that the service sector is expanding.

Perhaps the best cause for optimism, though, is to be found in the NFIB's inventory figures. 14% of NFIB members reported adding to their stocks in February, 3% more than in January. At the same time, the number reporting stock reductions fell 4%. These are the signs that companies are slowly finding the confidence that real economic growth might be on the way.