week 2 Flashcards
(24 cards)
What is ad hoc inference?
Intuitive reasoning based on inadequate data like casual observation or personal judgment.
What is statistical inference?
Scientific method using data sampled under controlled conditions, compared against chance distributions.
What does p < 0.05 mean?
Less than a 5% chance that the result is due to the null hypothesis (i.e., chance).
When is p < 0.01 used?
In high-stakes research like medicine; indicates 99% confidence.
What is simple random sampling?
Every member has an equal chance of selection.
What is systematic sampling?
Selecting every nth person to avoid bias.
What is stratified random sampling?
Sampling that reflects the demographic proportions of the population.
What Z-value corresponds to p = 0.05 significance level?
±1.96
What does it mean if a value falls beyond ±1.96?
It is statistically significant and unlikely due to chance.
What is considered a small effect according to Cohen’s d?
0.2
What does the correlation coefficient (r) measure?
The size and direction of a relationship between two variables.
How does correlation differ from the mean?
Mean describes one variable; correlation describes a relationship between two.
Does correlation imply causation?
No, only association.
When is Spearman’s Rho used?
When is Spearman’s Rho used?
When is Pearson’s R used?
For interval/ratio data with normal distribution.
What are Cohen’s guidelines for R?
0.1 = Weak
0.3 = Moderate
0.5 = Strong
What does R² represent?
The proportion of variance explained by one variable in another.
What are key assumptions for using Pearson’s r?
Independence of observations
Bivariate normality
Random sampling (often assumed)
What is the null hypothesis (H₀)?
Assumes no effect or difference
What is a Type I error?
Rejecting a true null hypothesis (false positive).
What is a Type II error?
Failing to reject a false null hypothesis (false negative).
What is statistical power?
The probability of correctly rejecting a false null hypothesis (1 - β).
- What does p ≤ α mean?
- What does p > α mean?
- Reject the null hypothesis.
- Retain the null hypothesis.
