Calculations

• What does a standard deviation close to 0 indicate about a data set?

  It indicates that the data points are very close to the mean of the data set.
• What does a high standard deviation indicate about a data set?

  It indicates that the data points are spread out over a wide range of values.
• What is the purpose of measuring variation using standard deviation?

  • To quantify the amount of variation or dispersion in a set of data values.
  • To understand how much individual data points differ from the mean.
• What can standard deviation be used for in graphical representations?

  It can be used to plot error bars on graphs.
• What is the purpose of statistical tests?

  To compare samples and determine relationships or differences.
• What does Spearman’s rank correlation coefficient measure?

  It measures the correlation between two variables.
• What does a student t-test tell you?

  It tells you if the difference between means is significant.
• What does the Chi-Squared test (𝝌²) analyze?

  It looks at differences in frequencies between groups.
• What are the key terms related to hypothesis testing?

  • Hypothesis: A testable statement about what will happen in an experiment.
  • Experimental hypothesis: Predicts a difference between groups or a correlation.
  • Null hypothesis: Predicts no significant differences or correlations.
  • Critical value: A benchmark for comparing test statistics.
  • Probability level: The likelihood that results are due to chance, usually 0.05.
  • Significance: Indicates results unlikely due to chance.
• What does the Spearman’s rank correlation coefficient (rs) value range from?

  The rs value ranges from 1 to -1.
• What does a strong positive correlation indicate about the rs value?

  The number will be closer to 1.
• What does a strong negative correlation indicate about the rs value?

  The number will be closer to -1.
• What should you do with the correlation result against the critical value?

  Compare it at a p=0.05 level to determine significance.
• What does the null hypothesis state in the context of correlation?

  It states that there is no correlation or relationship.
• What does the student t-test compare?

  It compares groups to see if the difference between means is significant.
• What are the two types of t-tests mentioned?

  Unpaired and paired t-tests.
• What does an unpaired t-test compare?

  It compares two groups from different individuals.
• What does a paired t-test compare?

  It compares two groups from the same individuals.
• Who is William Gosset and what is he known for?

  He is known as 'Student' and worked in quality control at the Guinness brewery.
• What does the t-test help determine?

  If there is a statistically significant difference between two means.
• What is the null hypothesis (H0) in the context of germination success?

  There is no statistically significant difference between the germination success of seeds in two soils of different pH.
• What is the alternative hypothesis (HA) in the context of germination success?

  There is a significant difference between the germination of seeds in two soils of different pH.
• What does the Chi-Squared test analyze?

  It determines if there is a significant difference in observed and expected results.
• What does the Chi-Squared value help to find?

  It helps to find the probability of observed results being due to chance.
• What is the formula for calculating degrees of freedom (dF) in Chi-Squared tests?

  The number of variables minus 1 (N-1).
• What is the requirement for data in Chi-Squared tests?

  The data should be independent, with each individual appearing only once.
• What is the formula for calculating expected frequencies in Chi-Squared tests?

  Expected frequencies are calculated based on the hypothesis being tested.
• What does Simpson’s index of diversity measure?

  It measures both species richness and evenness in a population.
• What does a high value of Simpson’s index indicate?

  A high value indicates a diverse habitat.
• What does a low value of Simpson’s index indicate?

  A low value indicates a habitat dominated by a few species.
• What is the process of mark and recapture (Lincoln index)?

  1. Capture a sample of animals (C1), mark them, and release them.
  2. After some time, recapture and count the total caught (C2) and how many are marked (C3).
  3. Total population = (C1 x C2) / C3.
• What are the steps to perform a Chi-Squared test?

  1. State the null hypothesis.
  2. Collect observed data.
  3. Calculate expected frequencies.
  4. Compute the Chi-Squared value.
  5. Compare the Chi-Squared value to the critical value.
  6. Accept or reject the null hypothesis based on the comparison.
• What are the key components of statistical analysis in hypothesis testing?

  • Formulate null and alternative hypotheses.
  • Choose appropriate statistical tests.
  • Analyze data and calculate test statistics.
  • Compare results against critical values.
  • Draw conclusions based on significance levels.