When T-test assumptions aren't met

Question 1

Data distributions: What is a positive skew?

Answer 1

Skewed to the right - mean is to the right of the median

like a right foot

Question 2

Data distributions: What is a negative skew?

Answer 2

Skewed to the left - mean is the left of the median

Question 3

What is positive/right skew bounded by?

Answer 3

Data is bounded by zero

Question 4

What is negative/left skew bounded by?

Answer 4

Data is bounded by the maximum value

Question 5

What is kurtosis?

Answer 5

It measures tail extremity, by representing the presence of outliers in a distribution

The larger the number (+ve or -ve) the less normally distributed the data

Question 6

Positive and negative kurtosis

Answer 6

if a dataset has a positive kurtosis, it has more in the tails than the normal distribution
negative kurtosis means that your distribution is flatter than a normal curve with the same mean and standard deviation

Question 7

Use of Mann-Whitney U test

Answer 7

If data is continuous
Mann-Whitney U test compares the sum of ranks

Mann-Whitney U test is used to compare whether there is a difference in the dependent variable for two independent groups.

Question 8

What is Levene’s test used for?

Answer 8

When performing a t-test, Levene’s test for equality of variance of data between
groups

Levene’s test tests for equal variance between samples