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Termini in questo insieme (20)

  • What are the main steps of the scientific method?

    Observation, Question, Hypothesis, Experiment, Data Analysis, and Conclusion.

  • What is a good scientific question?

    Based on observations or previous knowledge, answerable or measurable, leads to experiments, and involves a testable hypothesis.

  • Define the null hypothesis.

    The predicted conclusion that the treatment will have no effect. It is the negative hypothesis.

  • Define the alternate hypothesis.

    The hypothesis that is the opposite of the null, representing what you are actually testing for.

  • What is the difference between dependent and independent variables?

    Dependent variable: what the researcher measures; depends on another variable.
    Independent variable: what the researcher controls or varies; does not depend on another variable.

  • What is a parameter and what is a dimension in an experiment?

    Parameter: measurable characteristic of the system (e.g., concentration).
    Dimension: units of a parameter (e.g., grams, liters).

  • What are positive and negative controls?

    Positive control: treatment known to give a response, confirming the alternate hypothesis.
    Negative control: absence of treatment, confirming the null hypothesis.

  • How is the mean calculated?

    Sum of all values divided by the number of samples: \(\frac{\sum x_i}{n}\).

  • What is the median?

    The middle value of ordered data.

  • What does standard deviation measure?

    The average variation or spread of data points around the mean.

  • How does variation affect standard deviation?

    Larger variation results in a larger standard deviation; smaller variation results in a smaller standard deviation.

  • How is sample standard deviation calculated?

    Calculate squared differences from the mean, sum them, divide by n-1, then take the square root.

  • What is the standard error of the mean (SEM)?

    SEM = standard deviation divided by the square root of sample size: \(\frac{s}{\sqrt{n}}\).

  • What does overlap of means ± 2× SEM indicate about the null hypothesis?

    If the intervals overlap, the null hypothesis is not rejected (no significant difference).

  • What does no overlap of means ± 2× SEM indicate about the null hypothesis?

    If the intervals do not overlap, the null hypothesis is rejected (significant difference).

  • What is a Type I error in hypothesis testing?

    Rejecting the null hypothesis when it is actually true; the p-value is the probability of this error.

  • What is a Type II error in hypothesis testing?

    Accepting the null hypothesis when it is actually false; probability is 1 minus the p-value.

  • Why is sample size important in hypothesis testing?

    Sample size affects the standard error and confidence in rejecting or accepting the null hypothesis.

  • What is the role of statistical tests in biology?

    To determine p-values for inferences about the null hypothesis based on data distribution, variance, and experimental design.

  • How can you interpret a bar graph with error bars representing standard deviation?

    The bar height shows the mean; error bars show variability. Overlapping error bars do not necessarily mean no significant difference.