What is the null hypothesis in an ANOVA test?
- The means of all groups are different
- The means of all groups are equal
- The variances of all groups are different
- The variances of all groups are equal
The null hypothesis in an ANOVA test is that the means of all groups are equal. If the p-value obtained from the ANOVA test is less than the significance level, the null hypothesis is rejected, implying that there is a significant difference between at least two of the group means.
In a scatter plot, a __________ trend suggests a positive relationship between variables.
- Downward
- Horizontal
- Upward
- Vertical
In a scatter plot, an upward trend suggests a positive relationship between the variables. This means as one variable increases, the other variable also increases.
What is the role of eigenvalues in factor analysis?
- They are used to categorize the data
- They are used to transform the data
- They help in normalizing the data
- They represent the variance explained by each factor
In factor analysis, eigenvalues represent the total variance explained by each factor. A larger eigenvalue indicates that more of the total variance is accounted for by that factor.
Pearson's Correlation Coefficient assumes that the variables are ________ distributed.
- negatively
- normally
- positively
- randomly
Pearson's Correlation Coefficient assumes that the variables are normally distributed. It's one of the key assumptions made when calculating the coefficient, and it refers to the shape of the distribution of the values.
How does polynomial regression differ from linear regression?
- Linear regression models relationships as curves
- Linear regression models relationships as straight lines
- Polynomial regression models relationships as curves
- Polynomial regression models relationships as straight lines
Polynomial regression models relationships as curves, not straight lines. This allows polynomial regression to capture non-linear relationships, where the relationship changes direction at different levels of the independent variables. On the other hand, linear regression models relationships as straight lines, assuming a constant rate of change.
What is the Central Limit Theorem and how does it relate to the normal distribution?
- It states that all distributions are ultimately normal distributions
- It states that the mean of a large sample is always equal to the population mean
- It states that the sum of a large number of independent and identically distributed random variables tends to be normally distributed
- It states that the sum of a small number of random variables has an exponential distribution
The Central Limit Theorem states that, given certain conditions, the arithmetic mean of a sufficiently large number of iterates of independent random variables, each with a well-defined (finite) expected value and finite variance, will be approximately normally distributed, regardless of the shape of the original distribution.
What does ANOVA stand for?
- Analysis Of Variance
- Analysis Of Vitality
- Average Of Variance
- nan
ANOVA stands for Analysis Of Variance. It's a statistical technique used to check if the means of two or more groups are significantly different from each other.
What is the significance of the 68-95-99.7 rule in a normal distribution?
- It refers to the kurtosis of the distribution
- It refers to the outliers in the distribution
- It refers to the percentage of data within 1, 2, and 3 standard deviations of the mean
- It refers to the skewness of the distribution
The 68-95-99.7 rule, also known as the empirical rule, states that for a normal distribution, 68% of the data fall within one standard deviation of the mean, 95% fall within two standard deviations, and 99.7% fall within three standard deviations. This rule provides a quick estimate of the probability of a certain event within the distribution.
In a skewed distribution, the ________ tends to get pulled in the direction of the skew.
- Mean
- Median
- Mode
- nan
In a skewed distribution, the mean tends to get pulled in the direction of the skew. Since the mean involves every value in the distribution, extreme values (values far from the others) have a big influence. This results in skewness where the mean is drawn towards the tail, and is a common occurrence in distributions that are not symmetric.
What is a cumulative distribution function?
- It is the function that maps values to their percentile rank in a distribution
- It is the function that shows the cumulative probability associated with a function
- It is the maximum value a random variable can take
- It is the minimum value a random variable can take
The cumulative distribution function (CDF) of a random variable is the probability that the variable takes a value less than or equal to a certain value. The CDF of a function increases monotonically, and its limit is one as it approaches positive infinity.
What is the probability of an impossible event?
- 0
- 1
- Infinity
- Undefined
The probability of an impossible event is 0. In the probability scale, 0 denotes impossibility, while 1 denotes certainty. An event with a probability of 0 is said to be impossible because it cannot happen.
What assumptions must be met for Pearson's Correlation Coefficient to be valid?
- Both variables are independent
- Both variables are measured on a nominal scale
- Both variables are normally distributed, and there is a linear relationship between them
- Both variables have no outliers
For Pearson's Correlation Coefficient to be valid and reliable, the following assumptions should be met: both variables should be continuous, they should be linearly related, and both variables should be approximately normally distributed. Independence of observations is also required.