press release
http://www.cls.ioe.ac.uk/news.aspx?itemid=4646&itemTitle=One+in+four+girls+is+depressed+at+age+14%2c+new+study+reveals&sitesectionid=27&sitesectiontitle=News&returnlink=news.aspx%3fsitesectionid%3d27%26sitesectiontitle%3dNews

headlined ‘One in four girls is depressed’
and the first line
New research shows a quarter of girls (24%) and one in 10 boys (9%) are depressed at age 14

how do you diagnose depression ?

http://www.rcpsych.ac.uk/healthadvice/problemsdisorders/depressionkeyfacts.aspx

Click to access bluebook.pdf

Moods and Feelings Questionnaire 

 
3) third party info
parents didn’t match up – maybe something in that – some people do disguise their low mood very well but if fully functioning sleep appetite apparently enjoying life as normal very likely to be

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3734932/
sensitivity 0.75 specificity 0.73

validated in 1998 Manchester
1000 14 year olds
assume 5% have depression

group of 1000
test will pick up 36 of the 50 of them
will also pick up 238 as positive who are actually not depressed

http://www.sciencedirect.com/science/article/pii/S0165178198000730?showall%3Dtrue%26via%3Dihub Manchester

validation studies

and

https://www.ncbi.nlm.nih.gov/pubmed/16930387