Week 11 Flashcards
What kind of data is used in parametric tests?
Numerical data (interval or ratio).
What kind of data is used in non-parametric tests?
Categorical data (nominal or ordinal).
Parametric tests normally make assumptions, what are they?
Population parameters such as mean and normality of distribution.
List the 3 main reasons for using non-parametric tests.
- Numerical scores violate assumptions of mean and normality of distribution (unless solved with sample information).
- High level of variance in numerical data (converting numerical to ordinal data)
- Grouping is sometimes more convenient (scores, participants etc).
What does a Chi-square goodness-to-fit test measure?
Uses sample data to determine how well a sample proportions fit the population proportions based on the null hypothesis. (How well ƒₒ fits with ƒₑ)
What are the TWO hypothesises for a Chi-square goodness-to-fit test.
- Equal proportions/No preference (50/50 or 33.33/33.33/33.33 etc).
- No difference (to population proportions).
Is there a alternative hypothesis for a Chi-square goodness-to-fit test?
No.
What is observed frequency in a Chi-square goodness-to-fit test?
The data observed in the sample.
What is expected frequency in a Chi-square goodness-to-fit test?
What the distribution is expected to look like.
What symbol is used to represent expected frequency in Chi-squared tests?
ƒₑ
What symbol is used to represent observed frequency in Chi- squared tests?
ƒₒ
What symbol is used to represent Chi-squared?
𝜒²
What is the formula for Chi-squared?
𝜒² = ∑(ƒₒ-ƒₑ)² / ƒₑ
What is Chi-squared?
A theoretical, positively skewed distribution consisting of all possible random samples that would exist if the null hypothesis is true.
(Similar to a t-test distribution).
What does the Chi-squared of independence test measure?
Determines if a relationship exists between two categorical variables.
What is the null hypothesis for a Chi-squared of independence test?
X is NOT an independent variable for Y.
What is the alternative hypothesis for a Chi-squared of independence test?
X IS an independent variable for Y.
There is a relationship between the variables
How do you calculate ƒₑ for a Chi-squared of independence test?
ƒₑ = ƒ꜀ƒᵣ/n
What does ƒ꜀ represent?
Column frequency.
What does ƒᵣ represent?
Row frequency.
How do you calculate ƒₑ for a Chi-squared goodness to fit test?
ƒₑ = pn
proportion times sample
How do you calculate the df in a Chi-squared of independence tests?
df = (R-1)(C-1)
(Row sample size - 1 times column sample size -1
What is risk in statistics?
The probability that an event occurs.
What is a basic calculation of risk in words? (hint: it is the equation for probability).
Number of outcomes classified as A divided by the total number of outcomes.
