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study is conducte dto asses teh effectiveness of altering school luches for increasin the lipid conc in middle school students .a lo fat diet is compared to aa standard lunch .in order to minimise changes inlunch habits of students on the low fat diet ,the low fat lunch was given to 5 middle schools in the north side of the city and the regular lunches ( control group) were given to 5 school sin the south side of teh city...the results of teh study show that the study group had significantly lowered sr.cholesterol as compared to the control grp.what raises concern abt the validity of the the study results?

a0 biased measurement
b) lack of generalizability
c) lack of placebo
d) lack of randomisation
e) low power

i think it is D because he two groups are chosen base on geographic position so may be there are some other factors involved,gl

yea i think so too....I am not sure tho