biostats week 5bb part 1

What is the purpose of the chi-squared goodness of fit test?

To test hypotheses that an observed frequency distribution matches a claimed distribution.

In a chi-squared goodness of fit test, how is the null hypothesis defined?

The null hypothesis states that the observed proportion equals the expected proportion.

What does a large chi-squared statistic indicate about the p-value?

A larger chi-squared statistic results in a smaller p-value.

What type of data does the chi-squared goodness of fit test analyze?

It analyzes categorical data.

What are 'frequencies' in the context of categorical data?

Frequencies are the counts of occurrences in each category.

What is the formula for calculating degrees of freedom in a chi-squared test?

Degrees of freedom (df) = K - 1, where K is the number of levels of the outcome.

What would be the expected counts if we surveyed 100 people about smoking?

If 12.5% smokers are expected, we would expect 12.5 smokers out of 100 people.

When comparing continuous data, what statistical measures are primarily used?

Means and standard deviations.

In the context of good fit testing, what does 'K' represent?

K represents the number of categories in the outcome.

How do you calculate the test statistic in the chi-squared test?

Subtract the expected count from the observed count, square it, and divide by the expected count, summing for all categories.

What is the significance level commonly used in hypothesis testing?

The common significance level used is 0.05.

Why do we use cell counts in the chi-squared goodness of fit test?

Cell counts provide actual data used to compare against expected frequencies.

What would indicate that a test has failed to reject the null hypothesis?

If the p-value is greater than the significance level (alpha).

What type of distribution does the chi-squared distribution have?

It is always skewed to the right and not symmetric.

How does exposure to cigarette smoke affect weight gain in mothers according to the notes?

Exposure to cigarette smoke may cause reduced weight gain in the mother.