Exam 3
What is a Type 1 error?Rejecting the null hypothesis (H₀) when it is actually true (False Positive).
What is a Type 2 error? Failing to reject the null hypothesis when the alternative hypothesis (Hₐ) is true (False Negative).
Which error is worse in medical testing, and why?A Type 1 error is worse because it means approving an ineffective or harmful treatment.
If you incorrectly conclude that a new drug works when it actually doesn't, what type of error is that? Type 1 error.
How do you properly format a t-test result in APA style? t(df) = test statistic, p = p-value (e.g., t(28) = 2.45, p < .05).
What statistical symbols should always be italicized in APA formatting? t, F, p, M (mean), SD (standard deviation).
In APA style, should numbers below 10 be written as words or numerals? Words (except for statistical results).
What are two key types of statistics that should be reported in APA results? Descriptive statistics (mean, standard deviation) and inferential statistics (t, F, p-values).
What does H₀ represent? The null hypothesis, which states there is no effect or difference.
What is the difference between H₀ and Hₐ? H₀ states no difference; Hₐ states there is a difference or effect.
If you predict an effect, which hypothesis are you supporting? The alternative hypothesis (Hₐ).
If the null hypothesis is rejected, what does that mean? The data supports the alternative hypothesis (Hₐ), meaning a significant effect was found.
What is the difference between a directional and a non-directional hypothesis? A directional hypothesis predicts a specific direction of effect, while a non-directional hypothesis only predicts a difference without specifying direction.
When should you use a two-tailed test instead of a one-tailed test? When you are unsure of the direction of the effect.
Why might a researcher choose a non-directional hypothesis? If they don't have enough prior research to predict the direction of the effect.
What is the IV and DV in a study testing the effects of sleep on test scores? IV: Sleep (amount or quality). DV: Test scores.
How many levels does an IV need? At least two.
What is the mean of 5, 10, and 15? 10.
What is the median of 4, 6, 8, 10, 12? 8.
Which measure is best for skewed data? Median.
Which measure is most affected by outliers? Mean
What does a significant t-test result mean? There is a statistically significant difference between the groups.
What does p < .05 indicate? The result is statistically significant.
When should you use a paired samples t-test instead of an independent t-test? When comparing the same group at different times (e.g., pre-test vs. post-test).
If a t-test result is p = .12, what does that mean? The result is not statistically significant.
What type of data is eye color? Nominal.
What is the difference between interval and ratio data? Ratio data has a true zero; interval data does not.
Which scale allows for meaningful ratios? Ratio scale.
What scale is used for ranking in a competition? Ordinal
If p = .03, is the result significant? Yes, because p < .05.
If p = .08, what should you do with H₀? Fail to reject H₀ (not significant).
What does it mean if a result is not statistically significant? There is not enough evidence to reject H₀.
Why is .05 commonly used as the cutoff for significance? It balances the risk of Type 1 and Type 2 errors.
If you mistakenly conclude there is an effect, what error is that? Type 1 error.
If you fail to detect a real effect, what error is that? Type 2 error.
How do Type 1 and Type 2 errors relate to hypothesis testing? They represent incorrect conclusions in hypothesis testing.
Why is random assignment important? It reduces bias and increases validity.
When do you use an independent t-test? When comparing two separate groups.
What is the key assumption of an independent t-test? The two groups are independent and have equal variances.
If the levels are "morning, afternoon, evening," what is the IV? Time of day.
Why is it important to clearly define levels of an IV? To ensure accurate comparisons.
How do you convert an independent groups study into a dependent groups study? Test the same participants at different times instead of using separate groups.
What is an advantage of using dependent groups instead of independent groups? It controls for individual differences, increasing statistical power.