How can undercoverage bias occur during sampling?
- By including every individual in the population in the sample
- By not including certain segments of the population in the sample
- By selecting too large of a sample
- By selecting too small of a sample
Undercoverage bias can occur during sampling if certain segments of the population are not included in the sample or are represented less than they should be. This can result in a sample that is not representative of the population, leading to biased estimates.
The Z-score and T-score are both types of _______ scores, which measure the number of standard deviations an observation is from the mean.
- mean
- median
- standard
- variance
The Z-score and T-score are both types of standard scores. They measure the number of standard deviations an observation or statistic is from the mean.
A ________ ANOVA is used when we have two independent variables and want to understand if there is an interaction between them.
- Factorial
- One-way
- Three-way
- Two-way
A two-way ANOVA is used when there are two independent variables. This type of ANOVA assesses the main effects of each independent variable and the interaction effect between the variables.
What are confidence intervals used for in statistics?
- To determine the median of a sample
- To determine the spread of data in a sample
- To estimate the population parameter
- To find the mean of a sample
Confidence intervals are used to estimate the range within which the true population parameter lies with a certain degree of confidence. They do not specifically determine the mean, median, or spread of a sample.
How does skewness affect the mean and median of a dataset?
- In a positively skewed distribution, the mean is greater than the median
- In a positively skewed distribution, the median is greater than the mean
- Skewness affects only the mean
- Skewness does not affect the mean and median
In a positively skewed distribution, the mean is greater than the median as the mean gets pulled in the direction of the skew (towards the right tail). In a negatively skewed distribution, the mean is less than the median as the mean gets pulled towards the left tail.
What can cause the Chi-square test for goodness of fit to be biased?
- Having a large sample size
- Having a small sample size
- Having equal expected frequencies in all categories
- Having normally distributed data
A small sample size can lead to unreliable results in a Chi-square test for goodness of fit. This can be due to the fact that the test requires a sufficient number of observations in each category to provide a reliable estimate of the distribution.
A ________ distribution has a constant probability.
- Binomial
- Normal
- Poisson
- Uniform
A uniform distribution is a type of probability distribution in which all outcomes are equally likely. This implies a constant probability for all outcomes.
In the factor analysis, the _______ measures the amount of variance in all the variables which is accounted for by that factor.
- communality
- eigenvalue
- factor variance
- total variance
In the factor analysis, the eigenvalue measures the amount of variance in all the variables which is accounted for by that factor.
Why might you perform a paired t-test?
- All of the above
- To compare the means of the same group at two different times
- To compare the means of two different populations
- To compare two independent groups
A paired t-test is used to compare the means of the same group at two different times or under two different conditions. It is not used to compare independent groups or different populations.
The ________ of a random variable is the sum of the probabilities of all possible outcomes.
- Distribution
- Expected value
- Mean
- Variance
The "expected value" of a random variable is the sum of all possible values it can take, each multiplied by the probability of that outcome. It gives us the mean or average value of the random variable and is a fundamental concept in probability theory and statistics.