Calculate Variance and Standard Deviation

A confidence interval gives an estimated range of values which is likely to include an unknown population parameter.

In the context of multiple linear regression, we often compute confidence intervals for the coefficients of the independent variables.

It means we would be 95% confident that the true population effect of 'Car Age' on 'Sale Price' is between -$700 and -$300.

The significance level, often denoted as alpha, determines the threshold below which we reject or accept a null hypothesis in hypothesis testing.

The p-value represents the probability of obtaining results as extreme as the observed data, assuming the null hypothesis is true.

A nominal variable is a categorical variable without a natural ordering of its levels.

An ordinal variable is a categorical variable with levels that have a natural ordering.

The main difference is that ordinal variables have levels with a natural order, while nominal variables do not.

Selection bias occurs when non-random selection of participants leads to a non-representative sample.

Sampling bias causes results to be skewed due to the sample not being representative of the entire population.

Addressing these biases ensures that research findings are more reliable and generalizable.

The median_edu variable represents the median education level in a county, categorized as below_hs, hs_diploma, some_college, or bachelors.

To simplify analyses, nominal variables are treated as unordered to avoid assumptions of natural ordering.

Ordinal variables provide additional information due to their ordered levels, allowing for comparisons based on the natural hierarchy.

Understanding variable types helps in choosing appropriate analytical methods and interpreting results accurately.