There are many potential reasons why your map may not agree with a published map, but here are three possible experimental issues:
1. Sampling Bias: It is possible that your sampling method was bias and therefore resulted in a different distribution of data points than the published map. For example, there could be gaps in the data or certain areas were under-sampled.
2. Measurement Error: It is also possible that there were measurement errors in your data collection process, either due to mistakes made during actual measurement or due to faulty equipment. These measurement errors could potentially result in inaccurate data points that throw off your map.
3. Different Data Sets: It is possible that the published map and your map used different data sets or different data processing techniques that led to different results. This could be due to differences in the date of the data collection, differences in the spatial resolution of the data, or differences in the data processing software used.