Quantitative Lecture 8 Flashcards
Inferential Statistics and Tests of Difference
What is the difference between descriptive statistics and inferential statistics?
Descriptive statistics describe our sample(s), while inferential statistics make inferences about the population based on the sample.
What are some examples of descriptive statistics?
Examples include means, median, mode, variance, and frequencies.
E.g., what was the arousal level in the coffee and water group?
What was the mean score on the Mini-Mental State Exam (MMSE) for participants who were 97 years of age? - Skoog et al. (2017)
The mean score on the MMSE was 17.3.
What does inferential statistics allow us to do?
Inferential statistics allow us to make inferences about the population based on results from a representative sample.
What is the typical threshold for rejecting the null hypothesis in inferential statistics?
The typical threshold is p < 0.05.
What are some types of inferential statistics covered in this module?
Types include t-tests and correlations.
What are parametric tests based on?
Parametric tests are based on population parameters and assumptions about the underlying population.
What are non-parametric tests?
Non-parametric tests do not make strict assumptions about the data distribution.
What are the general parametric assumptions?
- Dependent variable should be interval or ratio level.
- Populations should be normally distributed.
- Variances should be approximately equal.
- No outliers or extreme scores.
What is a t-test?
A t-test is used to compare differences in means between groups.
What are the four assumptions for t-tests?
- Dependent variable should be interval or ratio data.
- Populations should be normally distributed.
- Variances should be approximately equal.
- No outliers or extreme scores.
What is the null hypothesis for t-tests?
The null hypothesis states that the population means from the two groups are equal.
What is Cohen’s d?
Cohen’s d is an effect size measure that indicates the magnitude of the difference between groups.
How should statistical results be reported?
- State the type of test performed.
- Report the test statistic, df, and significance.
- Report the mean difference and confidence intervals.
- Report the effect size.
- Comment on the means.
What is the full reporting format for a repeated measures t-test?
A repeated measures t-test showed a significant difference in anxiety levels, t (df) = value of t, p < .001. The mean difference (value, 95% CI) represented an effect size d = value.
