Statistics common mistakes

Common mistakes

• Distribution selection common mistake 1

  Writing a final answer without showing the method that justifies it. This can weaken answers for: N3 Select an appropriate probability distribution for a context, with appropriate reasoning, including recognising when the binomial or Normal model may not be appropriate..

  Fix itShow the method first, then give the final answer in the required form. Apply this directly to Distribution selection.

• Hypothesis testing language common mistake 1

  Writing a final answer without showing the method that justifies it. This can weaken answers for: O1 Understand and apply the language of statistical hypothesis testing, developed through a binomial model, including null hypothesis, alternative hypothesis, significance level, test statistic, one-tail test, two-tail test, critical value, critical region, acceptance region and p-value; extend to correlation coefficients as measures of how close data points lie to a straight line and interpret a given correlation coefficient using a given p-value or critical value, excluding calculation of correlation coefficients..

  Fix itShow the method first, then give the final answer in the required form. Apply this directly to Hypothesis testing language.

• Binomial hypothesis test for a proportion common mistake 1

  Writing a final answer without showing the method that justifies it. This can weaken answers for: O2 Conduct a statistical hypothesis test for the proportion in the binomial distribution and interpret results in context; understand that a sample is used to make an inference about the population and that the significance level is the probability of incorrectly rejecting the null hypothesis..

  Fix itShow the method first, then give the final answer in the required form. Apply this directly to Binomial hypothesis test for a proportion.

• Normal hypothesis test for a mean common mistake 1

  Writing a final answer without showing the method that justifies it. This can weaken answers for: O3 Conduct a statistical hypothesis test for the mean of a Normal distribution with known, given or assumed variance and interpret the results in context..

  Fix itShow the method first, then give the final answer in the required form. Apply this directly to Normal hypothesis test for a mean.

• Use of data in statistics common mistake 1

  Writing a final answer without showing the method that justifies it. This can weaken answers for: 3.21 Use one or more real, sufficiently rich large data sets in advance of final assessment; use technology such as spreadsheets or specialist statistical packages to explore the data set; interpret real data in summary or graphical form; use data to investigate questions arising in real contexts; analyse subsets or features of the data using a calculator with standard statistical functions..

  Fix itShow the method first, then give the final answer in the required form. Apply this directly to Use of data in statistics.