Alocal supermarket organised two weeks of promotions to boost sales. the average dailly salles before the carmpaign is $10 000, which becomes $11 000 during the promotion (average over 2 weeks). which analysis below is not useful for evaluating whether the increase in sales is statistically significant?

1. check the distribution of sales data.
2. inspect for possible outliers in sales data.
3. calculate precision of the prediction
4. monitor sales for longer period of time.

Arandomized controlled trial is designed to evaluate the effect of metoprolol in patients with heart failure. while preparing for statistical analysis, the researcher reviews some common types of statistical errors. which of the following statements is true regarding a type i error in a clinical study? a. the study is not significantly powered to detect a true difference between study groups. bthe null hypothesis is true but is rejected in error. c. the null hypothesis is false but is accepted in error. d. type i error is also known as beta and is usually 0.1 or 0.2. e. type i error depends on the study's confidence interval.