6 Questions
What is the purpose of constructing a confidence interval?
To provide a range of values within which a population parameter is likely to lie
When is a dependent samples t-test used?
When comparing the means of two related groups
What is the effect of having dependent samples on the standard error term?
It decreases the standard error
What is the purpose of a scatterplot in correlation analysis?
To identify the direction and strength of a correlation
What is the line of best fit in regression analysis?
The line that minimizes the sum of the squared errors
What is the Pearson's r correlation coefficient used for?
To measure the strength and direction of a linear relationship between two variables
Study Notes
Confidence Intervals
- Confidence intervals (CI's) are constructed for single mean when σX is known and when σX is not known
- CI's are also constructed for two sample means (independent and dependent)
- Confidence intervals have an interpretable meaning
Dependent Samples T-tests
- Identify designs that require an independent samples test or a dependent samples test
- Calculate correlated samples t-tests
- Calculate effect sizes for correlated samples tests
- Confidence intervals are calculated for correlated samples tests
- Factors influencing the power of a dependent samples t-test include:
- Having dependent samples changes the standard error term
- This affects the power of a test relative to independent samples tests
Correlation and Regression
- Scatterplots are used to interpret the direction and strength of a correlation
- Pearson's r correlation is calculated and interpreted when given means and standard deviations, or z scores
- Situations where Pearson's r may not be the best measure of correlation between X and Y include:
- Non-linear relationships
- Non-normal data
- Outliers
- Regression equation parts:
- Slope: the change in Y for a one-unit change in X
- Intercept: the value of Y when X is 0
- Regression equation is used to predict values of Y (Y')
- The line of best fit is the regression equation that minimizes the sum of the squared errors
Test your understanding of confidence intervals and dependent samples T-tests in statistics. This quiz covers constructing confidence intervals for single mean and two sample means, as well as identifying designs that require independent or dependent samples tests. Calculate correlated samples t-tests and confidence intervals for correlated samples.
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