Summary
Summary for Methods, Measurement and Statistics
- Course
- Institution
- Book
Summary for the Methods, Measurement and Statistics course for pre-master students at Tilburg University.
[Show more]
Connected book
Book Title:
Author(s):
- Edition:
- ISBN:
- Edition:
More summaries for
-
Methods, Measurement and Statistics
-
Causal Analysis Techniques
-
Every step you need for SPSS Casual Anal. Techn. for internaltional students (Stapsgewijze SPSS samenvatting (behaald met pass)
Seller
Follow
wendyvandosselaar
Content preview
Measurement levels: Norminal data (exhaustive & mutually exclusive), Ordinal data (logic, concrete order),Interval, Ratio (relative comarisons)
You can go from ratio to ordinal, but not the other way around
Measurement level is a property of the measurement values, it’s not an intrinsic property of the thing you
measure
Graph types: Bar charts (nominal & ordinal), Histogram (scale) & Scatterplots (scale)
Tables: Frequency table (1 variable) & Crosstable (2 variables)
The mean is no very robust/strong against outliers
The normal distribution: Symmetrical distribution, total area under curve is equal to 1
Central tendencies: Left skew, normal distribution, Right skep
Deviation score (D = X – M): The difference between each score X and M(ean) score. Is score of grams, so not
confuse it with Z-score. Total and average of deviations score is always 0.
Variance (S2): smaller values indicate less variation, people score closer to the mean (not yet a measure of
average variation)
Standard deviation (S): Smaller values indicate less variation, people score closer to the mean
Z-score (Z): the deviation score, but standardized by the variability of score. So not affected by the unit of scale.
Outcome: The number of standard deviations someone differs from the mean
You can calculate the percentage of people with particular score, and the propbability of observing
particular scores in your sample.
Step 1: Compute the Z-score of X (eg., height of 212 cm)
Step 2: Find the probability that a Z-score is larger than 1,6 (= Z)
P(X > Z > X) daarbuiten & P(X<Z<X) daarbinnen
Standard normal distribution (Z-distribution): Mean (µ) = 0. The average devation of the scores = 0. Standard
deviation (σ) = 1.
Empirical rules for normal distribution:
68% of the cases can be found within ± one SD from the mean. 95% of the cases can be found within ± two SDs
from the mean. 99,7% of the cases can be found within ± three SDs from the mean
With sampling distribution of the mean (population) use the standard error (and not SD). For example 95%
of the sample means can be found within 2 standard errors from the mean (CI)
Parameters Characteristics of populations
Statistics Sample estimates of the population characteristics
Descriptive statistics are limited to summarizing what’s directly observed. You don’t draw conclusions yet.
Inferential statistics are used to infer something about X in the whole population.
Two issues: Sampling bias (the sample is not representative of the population). Sampling fluctuations
(statistics have different estimates in different samples)
Sampling error = differences between sample value (e.g, mean) and population value
The sampling distribution of the mean = the distribution of the mean values across a large number of sample
of the same size from the same population.
(Population) Standard error (σM) = the standard deviation of a sampling distribution
Even if X is not normally distributed, the sampling distribution of the mean still approximates a normal
distribution if the sample size is large enough (say N > 30). (Central limit theorem?)
T-distribution: You can only use the formula of standard error of the mean if you know the population standard
deviation, but you rarely know this in practice. So, our best guess at σ is the sample estimate S. But, errors can
arise when we estimate σ using S.
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 wendyvandosselaar. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $7.82. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
80562 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now