Singles are a type of music release that typically have fewer tracks than an extended play or an album. For the first three years of the 1980s the UK Singles Chart was compiled by the British Market Research Bureau (BMRB) who had been compiling the charts throughout the 1970s. On 8 January 1983 Gallup took over the compilation of the UK music charts and continued to provide the chart data for the next eleven years. The charts were produced from the sales data of a representative panel of around 500 record shops across the country. The "panel sales" data from each shop were sent to the chart compilers were week and a multiplication factor was then applied to obtain an estimate of total sales across the country. Under the BMRB this sales data was posted to the chart compilers, but when Gallu