Class notes
Key Points for Research Methods
- Course
- Institution
Summary of important points for Research Methods. Includes topics on data collection, sampling distributions, and more. I earned a 75% for this course.
[Show more]
Seller
Follow
hannahkim2001
Content preview
Levels of measurement● Categorical: categories with no logical order
○ Ex: gender, voting, behavior
● Ordinal: categories with order but distance isn’t meaningful
○ Ex: highest level of qualification
● Interval: numbers with no absolute zero
○ Ex: IQ score
● Ratio: numbers with meaningful zero point
○ Ex: reaction time, number of siblings
Types of Data:
● Continuous: can take any value of range
○ Ex: heigh, speed
● Discrete: can only take certain values
○ Ex: number of people
Types of Study:
● Case study: detailed study of a specific person
○ Can’t use statistics and cannot generalize
● Quasi-experimental: allows independent and dependent variable to vary naturally
● Experimental: manipulation of independent variable, then allows dependent variable to vary
naturally
Within vs Between experiments
● Within: each person takes part in each condition
● Between: each person only takes part in one condition
Sampling distribution
● Sampling distribution of the mean: distribution of all possible sample means
○ Has a normal distribution
● Two rules
○ Mean of sample means = population mean
○ Standard deviation of sample means = standard deviation of the population/sqrt(sample
size)
● The larger the sample size, the narrower the distribution of sample means
Standard error: standard deviation of the sampling distribution of the mean → can estimate from a
sample → how accurate is our sample mean relative to the population mean
●
● Standard error decreases as sample size increases
● Interpreting standard error
, ○ We can be 68% confident that the population mean lies within 1 standard error of the
sample mean
Confidence intervals: gives an interval of plausible values for a parameter
● Interpreting a confidence interval (95%)
○ We are 95% confident that the interval [x,x] captures (tested hypothesis).
○ Of 100 intervals calculated the same way (95%), we expect 95 of them to capture the
population mean.
○ 95% chance that a normally-distributed quantity will fall within 1.96 standard deviations
of the mean
● Formula relies on accurately calculated population standard deviation (which is unknown) →
uses sample standard deviation as an estimate
○ When sample size is small → underestimate the variability of the data, so you use the
T-distribution
Hypothesis Testing
● Null Hypothesis (H0): alternative hypothesis is not true and observed value is consistent with
chance → “no difference”
● Alternative hypothesis (Ha): observed value is the result of a real effect, not just chance
P-values
● P-value: probability, assuming that H0 is true, that the statistic will take a value at least as
extreme as the observed results specified by H0
○ If p-value is very small, it is unlikely that the observed value would be so extreme if the
null hypothesis were true
● Alpha: controls type I error → we are willing to accept a Type I error about 5% of the time
● If p-value is smaller than alpha → results of the study are statistically significant
○ P-value < 0.05, then we reject the null hypothesis
○ P-value > 0.05, then we fail to reject null hypothesis
● P-value is not:
○ Evidence that the alternative hypothesis is TRUE
○ Evidence that the null hypothesis is TRUE
○ A measure of the size of an effect, or the importance of the result
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller hannahkim2001. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $11.29. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
79271 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now