Which one of the following is a validity condition for theory-based tests for regression? select one: a. the variability of the points around the regression line should not differ as you slide along the x-axis. b. the scatterplot should show a positive association between the explanatory and response variables. c. the variability of the explanatory variable should be the same as the variability of the response variable. d. there should be at least 10 successes and 10 failures in the data.

introduction, methodology, results, discussion

step-by-step explanation:

an observational study is one which consists of actual observation to record data and then analyse the data.

there are a number of factors that should be analyzed before starting an observational study.

the main four factors are:

i) introduction:   this should be analysed to check whether the purpose of the study is correctly established and the data recorded are appropriate for the study

methodology:   the method of collecting the data, such as whether randomly selected, and whether sample size matches with the population to be studied, whether questions asked are easy to answer by common men, etc.

results: then results such as summary of data with comments should be studied thoroughly

discussion:   the last is the discussion, this can be either by management people or persons who are all interested , etc.

the answer is 8/21

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