DA Statistical Analysis 1 — Questions and Answers
Question 1: What does a p-value less than 0.05 typically indicate in hypothesis testing?
- The null hypothesis is accepted
- The result is statistically significant (Correct answer)
- The sample size is too small
- The data is normally distributed
Correct answer: The result is statistically significant
A p-value below 0.05 means there is less than a 5% probability the observed result occurred by chance, so we reject the null hypothesis.
Question 2: Which measure of central tendency is most affected by extreme outliers?
- Median
- Mode
- Mean (Correct answer)
- Range
Correct answer: Mean
The mean sums all values and divides by count, so extreme outliers pull it significantly in their direction.
Question 3: What is the standard deviation a measure of?
- Central tendency
- Skewness of data
- Spread or dispersion around the mean (Correct answer)
- Correlation between variables
Correct answer: Spread or dispersion around the mean
Standard deviation quantifies how much individual data points deviate from the mean on average.
Question 4: A data analyst runs a t-test. What is the primary purpose of this test?
- Compare means of two groups (Correct answer)
- Test for normality
- Measure variable correlation
- Detect outliers
Correct answer: Compare means of two groups
A t-test is used to determine whether there is a statistically significant difference between the means of two groups.
Question 5: What does a correlation coefficient of -0.9 indicate?
- No relationship between variables
- Weak positive relationship
- Strong negative relationship (Correct answer)
- Perfect positive relationship
Correct answer: Strong negative relationship
A correlation of -0.9 is close to -1, indicating a strong inverse relationship where one variable increases as the other decreases.
Question 6: Which statistical distribution is symmetric and bell-shaped?
- Poisson distribution
- Binomial distribution
- Normal distribution (Correct answer)
- Exponential distribution
Correct answer: Normal distribution
The normal distribution is symmetric around its mean and produces the familiar bell-shaped curve.
DA Statistical Analysis 1
What does a p-value less than 0.05 typically indicate in hypothesis testing?