Statistics Quiz for MSc Students

In a biological experiment, what does the term "control group" refer to?

• The group of subjects exposed to the experimental treatment

• A group that is used as a reference to compare with the experimental group

• The group of subjects that receives a placebo

• The group of subjects that is not observed or measured

Answer explanation

In the context of a biological experiment, the term 'control group' is used to refer to a set of subjects that serve as a reference or baseline for comparison with the experimental group. This group is not exposed to the experimental treatment, helping to single out the effects of the treatment when comparing outcomes.

Which statistical test is appropriate for comparing the means of three or more groups in a biological study when the data meets the assumptions of normality and homogeneity of variances?

• Paired t-test

• Mann-Whitney U test

• Analysis of Variance (ANOVA)

• Chi-squared test

Answer explanation

The Analysis of Variance (ANOVA) is appropriate for comparing the means of three or more groups when the data meets the assumptions of normality and homogeneity of variances. This is because ANOVA can handle the complexity of multiple groups. The other options are not suitable for multiple group comparisons under these conditions.

What is the primary purpose of a Kaplan-Meier survival analysis in biological research?

• To compare the means of multiple groups

• To estimate survival probabilities over time

• To quantify gene expression levels

• To analyze protein-protein interactions

Answer explanation

The Kaplan-Meier survival analysis is a statistical method used in biological research to estimate the time it takes for an event to occur. This is often used to estimate survival probabilities over time, which is the correct answer to this question. This method is not used to compare group means, quantify gene expression levels, or analyze protein-protein interactions.

Which statistical concept is used to describe the variation or dispersion of data points around the mean in a dataset?

• Median

• Range

• Variance

• Mode

Answer explanation

The correct answer is Variance. Variance is a statistical concept used to describe the dispersion of data points around the mean in a dataset. It measures how far each number in the set is from the mean and thus from every other number in the set. This is different from the other options: Median and Mode are measures of central tendency, and Range only provides the difference between the highest and lowest values.

In a biological experiment, what does "blinding" refer to?

• Hiding the results from the researchers

• Ensuring that the experimental group is unaware of the treatment

• Keeping the researchers unaware of group assignments during data collection

• Conducting experiments in complete darkness

Answer explanation

"Blinding" in a biological experiment refers to the practice of keeping the researchers unaware of the group assignments during data collection. This is done to prevent any bias from affecting the results of the study. The researchers do not know which group is the control group and which one is receiving the treatment, ensuring the integrity of the data collected.

What statistical method is commonly used to determine if two continuous variables in a biological study have a linear relationship?

• Pearson correlation coefficient

• ANOVA (Analysis of Variance)

• Chi-squared test

• Mann-Whitney U test

Answer explanation

The Pearson correlation coefficient is often used in biological studies to understand if there is a linear relationship between two continuous variables. It measures the strength and direction of the linear relationship, making it the correct choice. The other options are statistical tests but not specifically for establishing this relationship.

Which statistical test is appropriate for comparing the means of two independent groups, such as the expression levels of a gene in two different tissues?

• Chi-square test

• ANOVA (Analysis of Variance)

• T-test

• Pearson correlation

Answer explanation

A T-test is specifically designed for comparing the means of two independent groups, such as different tissue types in this question. Other tests like Chi-Square test, ANOVA, or Pearson correlation are not appropriate for this specific comparison.

What is the purpose of a chi-square test in biology?

• To compare the means of two groups

• To test for a linear relationship between two continuous variables

• To compare observed and expected categorical data

• To calculate the median of a dataset

Answer explanation

A chi-square test in biology is used to compare observed and expected categorical data. It is not used to compare means, test for a linear relationship between two continuous variables, or calculate the median of a dataset. Thus, the correct answer is 'To compare observed and expected categorical data'.

In which of these situations should you use a non-parametric statistical test in biology?

• When your data is normally distributed

• When you have a small sample size

• When you want to compare means of multiple groups

• When you are testing for a linear relationship

Answer explanation

A non-parametric statistical test is used in biology when you have a small sample size. Non-parametric tests do not require the data to follow a specific distribution, making them suitable for small sample sizes where it's hard to determine if the data follows a normal distribution.

What does a p-value of 0.01 indicate in hypothesis testing?

• Strong evidence against the null hypothesis

• Weak evidence against the null hypothesis

• Strong evidence in favor of the null hypothesis

• A marginally significant result

Answer explanation

A p-value of 0.01 in hypothesis testing indicates there's only a 1% chance that the observed data would occur if the null hypothesis were true. Hence, it provides strong evidence against the null hypothesis. That's why the correct answer is 'Strong evidence against the null hypothesis'.