WJP Index Full Methodology

Methodology for Producing the Weekly Jewelry Purchasing Index

The WJP Index, begun in 2001, is a relative measure of consumers' most recent and expected jewelry purchasing. While measuring consumers’ seasonal buying patterns, both in actual sales and anticipated purchases, the WJP Index can empower its user to gain insight into consumer trends in the jewelry market—by week, by month, by season, by year. 

An online survey is sent to 6,000 randomly selected the Jewelry Consumers Opinion Council's database at the beginning of each week. The margin of error for this sample is +/-3%. Survey participants (U.S. domestic residents over 18 years old), are rotated each quarter so that no one consumer can take the survey twice in a calendar quarter. Each consumer is automatically entered into a JCOC drawing for a jewelry prize as an incentive to participate in and complete the survey. Survey results are not weighted to national totals.

Two questions are asked each week: (1) Did you buy any jewelry this past week?, and (2) How likely are you to buy jewelry this next week? An index is calculated for each question. To further enhance its value, we also offer the accompanying information of Gender, Income and Region for the consumers surveyed.

For “past purchase behavior”, an index is calculated by finding the proportion of those saying they bought jewelry in the past week, multiplying by 100, and rounding to the nearest whole number. This number is then divided by the base period average for the same question, multiplied by 100, and rounded to the nearest whole number. For example, if the proportion in the latest week is 0.3478, we use 35. If the average for the base is 44, then the index is (35/44)*100 = 0.795*100 = 80 rounded.

The Index's base period is March 2005 to September 2005. For this period, the percentages were calculated as described above for each week and then averaged. Since these months cover the middle of 2005, the WJP Index is relative to mid-year 2005.

The “future likelihood” question is handled the same way as the "past purchase behavior".

The overall Index is the ratio of the index for the likelihood to purchase question to the index for past purchase question.The Index is interpreted as consumer purchasing relative to the base period average. For the example of "past purchase behavior" detailed above, the index of 80 indicates that purchasing has decreased. An index of 100 indicates no change; anything above 100 indicates an improvement.

The results from the calculations are plotted on a time series graph each week. The pattern of the plotted lines indicates the trend in jewelry purchasing behavior among the surveyed consumers.

With its combination of short-term and long-term tracking of consumer behavior, the WJP Index is a powerful tool in building an effective stratagem for future marketing and growth. For more information on the WJP Index or how JCOC can expand its services to you, contact mailto:trade@jcoc.net.

The Jewelry Consumer Opinion Council (JCOC) Intelligence Center is the source for information about the gem and jewelry industry, concentrating on issues and trends that help industry professionals worldwide make critical and informed decision. The JCOC Intelligence Center provides Gem and Jewelry Industry Reports and Studies covering Jewelry Purchases, Jewelry Sales, Jewelry Buying Trends and more.