A longfather of old

I have a question.

My 23 and Me results said that my ancestry composition is:

78.4% British and Irish

19.9% French and German

1.7% Northwest European

but my Living DNA results are different, based on the download of my raw genetic data from 23 and Me:

97.5% Britain and Ireland

1.4% Northwest Germanic

1.7% Northwest European

I don't know which one is correct (and why they would differ)?

My 23andMe results are a bit different to the results of my uploaded 23andMe raw data to Living DNA too. 

I am not particularly knowledgeable about the reasons for the differences. I understand from the DNA company websites that the reason for the difference is along the lines of CatWoman’s explanation, ie, reference sample size and area covered. 

23andMe states that they calculate your ancestry by comparing your genome to the genomes of people whose ancestries they already know. Their datasets include genotypes from 14812 people who were chosen to reflect populations before travel and migration were common - at least 500 years ago, with 957 reference individuals of French, German, Belgian, Dutch and Swiss. British and Irish make up 1014.

23andMe states that their datasets are comprised largely of their own customers datasets. I would expect that this would lead to differences between your results from the same DNA, but I think we need an expert to interpret likely accuracy.

I see 23andMe allows you to manipulate the default confidence level in your downloaded raw data analysis from 50% to a conservative 90%.

LivingDNA state that all family ancestry results, from any company, are estimates, and are based on comparing your DNA to a set of reference samples.

The link gives information on testing from Ancestry UK. I am considering taking a new test with them as I already have some of my family ancestral tree completed, although it is mainly through the male line, thanks to a more unusual surname.

www.ancestry.co.uk/.../estimates

My 23andMe results are a bit different to the results of my uploaded 23andMe raw data to Living DNA too. 

I am not particularly knowledgeable about the reasons for the differences. I understand from the DNA company websites that the reason for the difference is along the lines of CatWoman’s explanation, ie, reference sample size and area covered. 

23andMe states that they calculate your ancestry by comparing your genome to the genomes of people whose ancestries they already know. Their datasets include genotypes from 14812 people who were chosen to reflect populations before travel and migration were common - at least 500 years ago, with 957 reference individuals of French, German, Belgian, Dutch and Swiss. British and Irish make up 1014.

23andMe states that their datasets are comprised largely of their own customers datasets. I would expect that this would lead to differences between your results from the same DNA, but I think we need an expert to interpret likely accuracy.

I see 23andMe allows you to manipulate the default confidence level in your downloaded raw data analysis from 50% to a conservative 90%.

LivingDNA state that all family ancestry results, from any company, are estimates, and are based on comparing your DNA to a set of reference samples.

The link gives information on testing from Ancestry UK. I am considering taking a new test with them as I already have some of my family ancestral tree completed, although it is mainly through the male line, thanks to a more unusual surname.

www.ancestry.co.uk/.../estimates