Chi-Squared Tests Flashcards

1
Q

How do you calculate the expected value for a cell?

A

(Row Total x Column Total) / Sample Size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do you calculate the chi-squared values for each cell?

A

(fo - fe) 2 / fe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the test statistic for chi-squared testing?

A

The sum of the chi-squared values

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the formula for the number of degrees of freedom?

A

(m - 1)(n - 1) where ‘m’ is rows and ‘n’ is columns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the critical value?

A

Using the formula booklet table, find the value given for the number of degrees of freedom and given significance level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the conclusion if the test statistic > critical value?

A

Reject H0 and suggests there is association

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the conclusion if the test statistic < critical value?

A

Reject H1 and suggests there is no association

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does a greater chi-squared values signify?

A

A greater chi-squared signifies a larger disparity between observed and expected values

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why can causation not be assumed if there is some association?

A

Causation cannot be assumed as a third variable may be involved

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does an expected frequency less than 5 suggest?

A

If they are less than 5, they are likely to be inaccurate because small samples create more random fluctuations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the solution to an expected frequency less than 5?

A

You combine categories suitably to give expected values greater than 5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What must you remember once you have combined categories?

A

You must re-evaluate the observed values as the categories for them have been combined too

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does chi-squared distribution assume about the data?
What does this mean for expected values less than 5?

A

Chi-squared distribution assumes that the sum of the squares are of normal distribution
If fe > 5, distribution of fo is asymmetrical so needs to be combined

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does a goodness of fit test, test?

A

Goodness of fit test tests whether a given set of data fits a particular distribution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What variables have an impact on the procedure of the goodness of fit test?
What is the impact?

A

When the mean is estimated for poisson and probability for binomial, you subtract one from the number of degrees of freedom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the recurrence relation for Poisson Distribution?

A

P(X = r + 1) = P(X = r) x (y / r + 1)

17
Q

When do you combine categories?

A

When expected frequency is less than 5