<prompt> Similarity between Cross sectional study design and Ecological study design:-Both studies are done at a point of timeBoth provide prevalenceBoth are based on primary dataUnit of study is population  <response>: Cross Sectional Study Ecological Study Both studies are done at a point of time - Done based on primary Data i.e. collected by Investigation himself from House to House. - It provides Prevalence, so aKa Prevalence Study - aKa SNAPSHOT Study. - Done based on Secondary Data i.e. Collected data from records of hospital Data is not collected by Investigator himself. - Used in Nutritional Surveys - Cannot calculate strength of association prevalence - Unit of Study is population and results are extrapolated projected not on Individuals but on total population. This drawback is known as Ecological Fallacy. 