By: Liz Farmer

Not shockingly, it’s really anybody’s guess as to how back-to-school sales will turn out this August. With the stock market and consumer confidence levels bouncing back and forth between the plus-side and the minus-side, it seems like a Magic 8 Ball would be just as good at predicting the retail future as a trained economist.

But here’s what the economists are saying this week: The International Council of Shopping Centers says this season’s sales (from mid-July to mid-September) will increase by 5.4 percent. That would be the biggest percentage increase (not dollar increase) since 2005, according to the ICSC. The council based its prediction on recent sales of family clothing, shoes, electronics and books as reported by the U.S. Commerce Department. Sales in those segments collectively declined by 2.8 percent in 2009 and 0.4 percent in 2008 during the July-September period.

“Based on arithmetic alone, the expected July jump in [back-to-school] spending could be extremely strong,” Michael P. Niemira, chief economist and director of research for ICSC, said in a statement. “Layer on some fundamental improvement in the consumer economy, including some pickup in the pace of earnings growth, and we should see a strong 7.6 percent rise for July, continued strength in August with a 5.7 percent increase, and a moderate 3 percent rise in September.”

Meanwhile the National Retail Federation says that summer sales so far make it hard to predict back-to-school spending. According to the NRF, June retail industry sales (which exclude automobiles, gas stations and restaurants) decreased 0.5 percent seasonally adjusted over May and increased 3.3 percent unadjusted year-over-year.

“Today’s data shows consumers continue to take a cautious approach towards shopping,” said NRF President and CEO Matt Shay. “However, growth in key areas such as electronics, apparel and department stores is an encouraging sign as we enter the back-to-school shopping season.”

So, in other words, who the heck knows how the rest of summer will play out? It seems that some kind of year-over-year increase is in our future but just how big that increase will be is pretty uncertain.

And considering the sales declines of the last two summers, a minimal increase over terrible sales would be, well, less terrible. But not necessarily anything to write home about.