When T-test assumptions aren't met Flashcards

1
Q

Data distributions: What is a positive skew?

A

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

like a right foot

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2
Q

Data distributions: What is a negative skew?

A

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

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3
Q

What is positive/right skew bounded by?

A

Data is bounded by zero

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4
Q

What is negative/left skew bounded by?

A

Data is bounded by the maximum value

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5
Q

What is kurtosis?

A

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

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6
Q

Positive and negative kurtosis

A

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

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7
Q

Use of Mann-Whitney U test

A

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.

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8
Q

What is Levene’s test used for?

A

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

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