Growth of mobile technology is forcing retailers to change and transform.

WASHINGTON — Families with school-age children and college consumers are lagging slightly behind on their back-to-school shopping this year and online shopping is playing a bigger role in their purchases, according to a new National Retail Federation survey.

Despite an earlier start to back-to-school shopping, the average family with children in grades K-12 has completed nearly half, or 48 percent, of their shopping as of early August, slightly down from 50 percent at this time last year, the NRF survey showed.

Seventy percent of families still need to purchase clothing, while 57 percent have to buy shoes and 77 percent need to buy school supplies, according to the survey conducted by Prosper Insights & Analytics. It was the first time the survey posed the question to consumers.

The survey, conducted Aug. 2-9, asked 6,915 consumers about their back-to-school shopping plans.

“It is evident that many families are still considering price and value when shopping for their back-to-school and college needs,” said Matthew Shay, president and chief executive officer at the NRF. “Shopping early and often is a trend we have seen from many budget-conscious consumers over the last few years. In the weeks ahead, parents will take advantage of the aggressive deals that retailers will offer as they get ready to welcome the fall season merchandise.”

The survey registered the highest percentage of respondents in its history who said they will shop online.

More families said they will shop online this year — 31 percent compared with 27 percent last year — which marked the highest percentage in the survey’s history.

Retailers could see a big boost in the latter half of the back-to-school season, including discount stores, where 53 percent of respondents said they will finish their shopping. Fifty-one percent of respondents said they will make purchases from department stores, while 39 percent said they will go to clothing stores and 37 percent said they will shop at office supply stores.

Some 13 percent of families have completed their shopping lists but 22 percent of families have not started shopping, up from 20 percent last year, according to the survey.

Bargain hunting is key with 48 percent of parents saying they are influenced by coupons, up from 43 percent last year and “the highest in the survey’s history.”

Thirty-nine percent said they will take advantage of in-store promotions and 33 percent said they will utilize advertising inserts to complete their shopping lists, the survey found.

Half of the purchases made from those starting early were spurred by coupons, sales and promotions.

When asked what payment method families will use most often to complete their purchases, 49 percent said they will use debit cards while 29 percent said they will use credit cards. The anticipated use of cash (21 percent) and checks (2 percent) reached the lowest levels in the survey’s history.

Similarly, the college spending survey update showed that students and families with children in college have completed about 48 percent of their shopping, down from 49 percent last year, according to the survey. Fifteen percent of consumers preparing for college have completed their shopping lists, compared with 19 percent at this time last year.

“When it comes to big spending events such as back-to-school and back-to-college, families are being very savvy in how they tackle their lists,” said Pam Goodfellow, a principal analyst at Prosper. “Families are slowly completing their shopping this season while taking [advantage] of expected promotions that will continue through Labor Day, and spreading their budget as necessary.”

Fifty percent said they still need to purchase clothing, while 33 percent need to buy personal-care items and 61 percent need school supplies, the survey found.

Forty-two percent of college-bound consumers will likely complete the rest of their shopping at discount stores — the lowest in the survey’s history — while another 42 percent will likely finish buying items at department stores — the highest in the survey’s history.

Forty percent of college students and their families said they will purchase the rest of what they need online, up from 37 percent last year, marking another survey record.

Coupons and promotions are also coming into play among consumers preparing for college. Of those who have already done their shopping, 50 percent said they were influenced by promotions, up from 48 percent last year.

And for those college consumers that still need to complete their shopping, 42 percent said they are using coupons to complete their shopping list, while 32 percent said they will take advantage of in-store promotions, followed by 29 percent who will utilize advertising inserts.

Forty four percent said they will use debit/check cards, while the use of credit cards continued to increase with 36 percent of respondents saying they used them for purchases.