Summary
Summary of SPSS for introduction to statistics / Statistics 1 & 2 (for LAS)
- Course
- Institution
Summary of SPSS for introduction to statistics / Statistics 1 & 2 (for LAS)
[Show more]
Seller
Follow
fleursmilde
Content preview
Notes on SPSS / bps.uvt.nlSession 1: Introduction to SPSS and descriptives
Every variable has a measurement level.
Bar chart: graphs -> legacy dialogs -> bar.
Bar chart ( % on y-axis): graphs -> legacy dialogs -> Bar -> (again) Simple -> Define -> “% of cases” -> OK.
Histogram: graph -> legacy dialogs -> Histogram (-> display normal curve).
Scatterplot: graph -> legacy dialogs -> scatter/dot -> Simple Scatter -> define X/Y axis variables.
Descriptives: analyze -> descriptive statistics -> descriptives (-> options -> variance) – check for errors!
Frequency table: Analyze -> Descriptive Statistics -> Frequencies
Order cases for a variable (highest measure -> lower measure): Data -> sort cases
Compare groups: Data -> Split File -> Compare Groups. (2 groups will appear in the output)
Undo the split file: data -> split file -> “Analyze all cases, do not create groups”.
Percent (observed frequency / N) vs Valid Percent (observed frequency / Valid N) (no missing values)
Median: middle number in a sorted list of numbers
Mode: most common observation
Variance: Sum of (x-x-(mean))2 / N-1 5-3-1: x-(mean) = 3, variance = (5-3)2 + (3-3)2 + (1-3)2 = 8
Standard deviation: √ ❑ Variance
Correlation coefficient: r (0<1): analyze -> correlate -> bivariate (Pearson Correlation)
Session 2: SPSS skills and normal distribution
Random variable: numerical outcome of a chance experiment
Continuous variable: can take on infinitely many values (height of a person)
Discrete variables: can take on only particular values (number of correct guessed answers)
When SD increases, the distribution becomes wider.
68% of the values lie within one standard deviation from the mean.
95% of the values lie within two standard deviations from the mean.
Empty cell in data = system missing. User-missing code: 999. Define in SPSS in variable view […]
Recode missing: check how many missing (frequency).
Transform -> recode into the same variables -> select variable(s) -> “Old and new values” -> (to recode
System Missing into 999) -> “system missing” = old Value, 999 = new value.
How many missing? Transform -> Count Values within Cases -> name target variable -> select variables.
Percentage missing: analyze -> descriptive statistics -> frequencies (choose target variable)
Delete case of a missing value: data -> select cases -> “If condition is satisfied” -> ‘if’ -> variable = 0 (filter
out unselected cases) SPSS has crossed out the cases & added variable ‘filter_$’ (1= included, 0= not).
Delete unselected cases: Data -> select cases -> “Delete Unselected Cases”.
Incongruent direction of measuring variable: Transform -> Recode into different Variables -> select
variable to be recoded -> specify name & label -> change (0->2 – 1->1 – 2->0) (New column in data view)
Values for whole category: Transform -> compute variable -> choose a name for the category
, Notes on SPSS / bps.uvt.nl
Session 4: Type-I/type-II, one-sample t-test, independent samples t
Statistical hypotheses pertain to population parameters.
Type I Error: rejecting the null-hypothesis, while it is true. (False negative)
Type II Error: not rejecting the null-hypothesis, while it is not true. (False positive)
Both errors are inversely related, higher alpha/p more type I, less type II.
Alpha levels aren’t right or wrong, but do have to be justified.
T-test: analyze -> compare means -> one-sample T-test -> specify test variable & value (of hypothesis).
Independent samples t-test: analyze -> compare means -> independent samples t-test -> select variable
and grouping variable -> define groups (1= 1, 2=2) [results: descriptive, testing significance, importance]
Effect-size measures: expresses size of effect in “standardized way”. Results can be compared like this.
-Cohen’s D: standardized difference between two group means. =0.5 0.5 SD away from mean.
(0.2 = small, 0.5 = medium 0.8 = large)
Session 5: T-tests and ANOVA
Syntax is a series of “commands” that tells SPSS what to do. Important for: efficiency, communication,
documentation & data management, necessity.
Syntax for descriptives: analyze -> descriptive statistics -> descriptives -> paste -> RUN syntax.
Syntax comments begin with *, end with . Here you can add VARIANCE to statistics list e.g.
Basic syntax: analyze -> General Linear Model -> Univariate
Comparing multiple groups: Analyze -> General Linear Model -> Univariate -> options: descriptive
statistics & homogeneity tests -> PASTE -> Run
Levene’s test significant (a>p): population variances of the groups should not be considered equal.
ANOVA is robust against such a violation, if the group sizes are roughly the same.
Sig. value of the “Corrected Model” in the first row = 2-sided p value for rejecting the null-hypothesis.
R squared / R2 (/ἠ2) = explained variance by group membership. [Small-0.01, Medium-0.06, Large-0.14]
Only look at cases in a certain scenario (weather): Data -> Select Cases -> “If condition is satisfied” -> “If”
-> enter condition into the equation box (weather = 1, only good weather e.g.). -> continue -> paste.
3 sources of variation: Sums of Squares total (SSt) [Corrected Total, column Type III SS], Sums of Squares
between (SSb)[group mean vs grand mean], Sums of Squares within (SSw)[individual vs grand mean].
MSb=SSb/(k−1) MSw=SSw/(N−k) F=MSb/MSw dfb=k−1 dfw=N−k
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 fleursmilde. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $5.79. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
53340 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now