The JoHo Insurances Foundation is specialized in insurances for travel, work, study, volunteer, internships an long stay abroad
Check the options on joho.org (international insurances) or go direct to JoHo's https://www.expatinsurances.org
Workgroup notes with Experimental & Correlational Statistics at the Leiden University - 2018/2019
Access options
How do you get full online access and services on JoHo WorldSupporter.org?
1 - Go to www JoHo.org, and join JoHo WorldSupporter by choosing a membership + online access
2 - Return to WorldSupporter.org and create an account with the same email address
3 - State your JoHo WorldSupporter Membership during the creation of your account, and you can start using the services
- You have online access to all free + all exclusive summaries and study notes on WorldSupporter.org and JoHo.org
- You can use all services on JoHo WorldSupporter.org (EN/NL)
- You can make use of the tools for work abroad, long journeys, voluntary work, internships and study abroad on JoHo.org (Dutch service)
Already an account?
- If you already have a WorldSupporter account than you can change your account status from 'I am not a JoHo WorldSupporter Member' into 'I am a JoHo WorldSupporter Member with full online access
- Please note: here too you must have used the same email address.
Are you having trouble logging in or are you having problems logging in?
Toegangsopties (NL)
Hoe krijg je volledige toegang en online services op JoHo WorldSupporter.org?
1 - Ga naar www JoHo.org, en sluit je aan bij JoHo WorldSupporter door een membership met online toegang te kiezen
2 - Ga terug naar WorldSupporter.org, en maak een account aan met hetzelfde e-mailadres
3 - Geef bij het account aanmaken je JoHo WorldSupporter membership aan, en je kunt je services direct gebruiken
2 - Ga terug naar WorldSupporter.org, en maak een account aan met hetzelfde e-mailadres
3 - Geef bij het account aanmaken je JoHo WorldSupporter membership aan, en je kunt je services direct gebruiken
- Je hebt nu online toegang tot alle gratis en alle exclusieve samenvattingen en studiehulp op WorldSupporter.org en JoHo.org
- Je kunt gebruik maken van alle diensten op JoHo WorldSupporter.org (EN/NL)
- Op JoHo.org kun je gebruik maken van de tools voor werken in het buitenland, verre reizen, vrijwilligerswerk, stages en studeren in het buitenland
Heb je al een WorldSupporter account?
- Wanneer je al eerder een WorldSupporter account hebt aangemaakt dan kan je, nadat je bent aangesloten bij JoHo via je 'membership + online access ook je status op WorldSupporter.org aanpassen
- Je kunt je status aanpassen van 'I am not a JoHo WorldSupporter Member' naar 'I am a JoHo WorldSupporter Member with 'full online access'.
- Let op: ook hier moet je dan wel hetzelfde email adres gebruikt hebben
Kom je er niet helemaal uit of heb je problemen met inloggen?
Join JoHo WorldSupporter!
What can you choose from?
JoHo WorldSupporter membership (= from €5 per calendar year):
- To support the JoHo WorldSupporter and Smokey projects and to contribute to all activities in the field of international cooperation and talent development
- To use the basic features of JoHo WorldSupporter.org
JoHo WorldSupporter membership + online access (= from €10 per calendar year):
- To support the JoHo WorldSupporter and Smokey projects and to contribute to all activities in the field of international cooperation and talent development
- To use full services on JoHo WorldSupporter.org (EN/NL)
- For access to the online book summaries and study notes on JoHo.org and Worldsupporter.org
- To make use of the tools for work abroad, long journeys, voluntary work, internships and study abroad on JoHo.org (NL service)
Sluit je aan bij JoHo WorldSupporter! (NL)
Waar kan je uit kiezen?
JoHo membership zonder extra services (donateurschap) = €5 per kalenderjaar
- Voor steun aan de JoHo WorldSupporter en Smokey projecten en een bijdrage aan alle activiteiten op het gebied van internationale samenwerking en talentontwikkeling
- Voor gebruik van de basisfuncties van JoHo WorldSupporter.org
- Voor het gebruik van de kortingen en voordelen bij partners
- Voor gebruik van de voordelen bij verzekeringen en reisverzekeringen zonder assurantiebelasting
JoHo membership met extra services (abonnee services): Online toegang Only= €10 per kalenderjaar
- Voor volledige online toegang en gebruik van alle online boeksamenvattingen en studietools op WorldSupporter.org en JoHo.org
- voor online toegang tot de tools en services voor werk in het buitenland, lange reizen, vrijwilligerswerk, stages en studie in het buitenland
- voor online toegang tot de tools en services voor emigratie of lang verblijf in het buitenland
- voor online toegang tot de tools en services voor competentieverbetering en kwaliteitenonderzoek
- Voor extra steun aan JoHo, WorldSupporter en Smokey projecten
Meld je aan, wordt donateur en maak gebruik van de services
Access:
JoHo members
Join WorldSupporter!
Work for WorldSupporter
JoHo can really use your help! Check out the various student jobs here that match your studies, improve your competencies, strengthen your CV and contribute to a more tolerant world
Search other summaries?
This content is also used in .....
Experimental and Correlational Research: Summaries, Study Notes & Practice Exams - UL
Lecture notes with Experimental and Correlational Research at the Leiden University - 2018/2019
Lecture notes with Experimental and Correlational Research at the Leiden University - 2018/2019
Lecture 1
6/2/2019
-Correlation is about two variables being associated, but there is no evidence of causality.
-Causality however requires multiple factors: covariance (variables have an association), directionality(cause precedes effect (in time)) and internal validity(eliminate alternative explanations).
- Correlations can be displayed in scatterplots that show:
- Direction: positive or negative
- Strength: density of the points
- Shape: linear/nonlinear and homogeneous (one cluster) / heterogeneous (multiple clusters).
- Outliers
-Covariance (sxy): to measure the degree to which two variables vary together.
Formula: sxy = Σ(xi-x)(yi-y) / N-1
It provides us with information on the strength and direction of the association. The disadvantage is that the covariance is dependent on the unit of measurement of the variables.
-Pearson r is a standardized measure that describes the linear relationship between two quantitative variables, and always lies between -1 and +1.
Formulas: r = sxy / sxsy Alternative: r = Σzxzy / N-1
- Remember that a z-score is a standardized score that displays how many standard deviations a certain score is away from the mean.
Alternative correlational techniques:
- The Pearson r is the correlation coefficient that is most commonly used. There are alternatives:
quantitative + quantitative --> Pearson r
ordinal + ordinal --> Spearman’s rho (rs)
dichotomous(only two possible values)+ quantitative --> point-biserial correlation (rpb)
dichotomous + dichotomous --> phi coefficient (ϕ)
-Spearman’s rho (rs) describes relationship between two ordinal variables/ranked scores.
Formulas: xrank = N + 1 / 2 srank = √ (N(N+1) / 2)
rs = r on ranked data
Spearman’s rho is also an alternative to Pearson r in case of outliers and/or weak non-linearity.
-Point-biserial correlation describes relationship between quantitative and dichotomous variables. We use the Pearson correlation formula to calculate rpb: rpb = r
The sign of the correlation (+/-) depends on the way 0 and 1 are assigned to groups.
Relationship rpb and tindependent: rpb = Square root of t2 / t2 + df
-Phi-coefficient (ϕ) describes relationship between two dichotomous variables: ϕ
.....read moreAccess:
JoHo members
Workgroup notes with Experimental & Correlational Statistics at the Leiden University - 2018/2019
Workgroup notes with Experimental & Correlational Statistics at the Leiden University - 2018/2019
Week 1
Prep exercises
- Which combination of measurement levels is required for the use of the Pearson, Spearman, and point-biserial correlation respectively?
- Which formula is suitable for calculating the Pearson, Spearman, and point-biserial correlations?
- Which formula describes the relationship between rpb and tindep?
- Which combination of measurement levels is required for the use of the phi coefficient?
- What is the specific formula for calculating the phi coefficient?
- Which formula describes the relationship between φ and χ2?
- What is the formula for testing the difference between two independent correlation coefficients?
- What is the rule of thumb for effect size r2 and r?
Workgroup tips 1
Correlation is NOT causation. It is an association between variables.
Positive correlation = both increase or decrease
Negative = One increases, the other decreases
Pearson’s r; both variables are at an interval level. Formula: ∑ZxZy/n-1
Spearman rho = two ordinal variables (To avoid outlier influence in Pearson’s r) rs = r Important: RANK IT FIRST, then take the z scores
Point Biserial; one dichotomous and one continuous variable rpb = r
Phi is a nominal variable, that only has two levels each aka dichotomous X2 = r
Dichotomous means that the value can only be one of two things. For instance yes/no, male/female, left/right. It is a nominal variable, but where with a simply nominal variable answers can be red/blue/green/yellow, a dichotomous variable could in this case only be red/blue, for instance.
Basically, all of these correlation have the basic formula, which is ∑ZxZy/n-1
R is about sample, ρ is population
Parameter | Population | Sample |
Mean | µ | x̄ |
Probability | P | p |
Standard Deviation | σ | S |
Correlation |
Access:
JoHo members
What is a correlational research design?
What is a correlational research design?
A correlational research design investigates the relationship between two or more variables without directly manipulating them. In other words, it helps us understand how two things might be connected, but it doesn't necessarily prove that one causes the other.
Imagine it like this: you observe that people who sleep more hours tend to score higher on tests. This correlation suggests a link between sleep duration and test scores, but it doesn't prove that getting more sleep causes higher scores. There could be other factors at play, like individual study habits or overall health.
Here are some key characteristics of a correlational research design:
- No manipulation: Researchers observe naturally occurring relationships between variables, unlike experiments where they actively change things.
- Focus on measurement: Both variables are carefully measured using various methods, like surveys, observations, or tests.
- Quantitative data: The analysis mostly relies on numerical data to assess the strength and direction of the relationship.
- Types of correlations: The relationship can be positive (both variables increase or decrease together), negative (one increases while the other decreases), or nonexistent (no clear pattern).
Examples of when a correlational research design is useful:
- Exploring potential links between variables: Studying the relationship between exercise and heart disease, screen time and mental health, or income and educational attainment.
- Developing hypotheses for further research: Observing correlations can trigger further investigations to determine causal relationships through experiments.
- Understanding complex phenomena: When manipulating variables is impractical or unethical, correlations can provide insights into naturally occurring connections.
Limitations of correlational research:
- It cannot establish causation: Just because two things are correlated doesn't mean one causes the other. Alternative explanations or even coincidence can play a role.
- Third-variable problem: Other unmeasured factors might influence both variables, leading to misleading correlations.
While correlational research doesn't provide definitive answers, it's a valuable tool for exploring relationships and informing further research. Always remember to interpret correlations cautiously and consider alternative explanations.
What is the correlational method?
What is the correlational method?
In the realm of research methodology, the correlational method is a powerful tool for investigating relationships between two or more variables. However, it's crucial to remember it doesn't establish cause-and-effect connections.
Think of it like searching for patterns and connections between things, but not necessarily proving one makes the other happen. It's like observing that people who sleep more tend to score higher on tests, but you can't definitively say that getting more sleep causes higher scores because other factors might also play a role.
Here are some key features of the correlational method:
- No manipulation of variables: Unlike experiments where researchers actively change things, the correlational method observes naturally occurring relationships between variables.
- Focus on measurement: Both variables are carefully measured using various methods like surveys, observations, or tests.
- Quantitative data: The analysis primarily relies on numerical data to assess the strength and direction of the relationship.
- Types of correlations: The relationship can be positive (both variables increase or decrease together), negative (one increases while the other decreases), or nonexistent (no clear pattern).
Here are some examples of when the correlational method is useful:
- Exploring potential links between variables: Studying the relationship between exercise and heart disease, screen time and mental health, or income and educational attainment.
- Developing hypotheses for further research: Observing correlations can trigger further investigations to determine causal relationships through experiments.
- Understanding complex phenomena: When manipulating variables is impractical or unethical, correlations can provide insights into naturally occurring connections.
Limitations of the correlational method:
- Cannot establish causation: Just because two things are correlated doesn't mean one causes the other. Alternative explanations or even coincidence can play a role.
- Third-variable problem: Other unmeasured factors might influence both variables, leading to misleading correlations.
While the correlational method doesn't provide definitive answers, it's a valuable tool for exploring relationships and informing further research. Always remember to interpret correlations cautiously and consider alternative explanations.
Summaries and study services for IBP Bachelor 1 at Leiden University - Year 2022/2023
Summaries and study services for IBP Bachelor 1 at Leiden University - Year 2022/2023
- This page contains study materials for the study IBP Bachelor 1 at Leiden University (UL).
- For Dutch summaries and study services, please see Samenvattingen en studiehulp voor Psychologie Bachelor 1 aan de Universiteit Leiden
- For a full overview of available study materials for this study, please visit the Summary Shop on JoHo.org.
College- en werkgroepaantekeningen bij Experimenteel en Correlationeel Onderzoek - UL
Collegeaantekeningen Experimenteel en Correlationeel Onderzoek, Psychologie Leiden
Collegeaantekeningen Experimenteel en Correlationeel Onderzoek, Psychologie Leiden
In de bijlagen vind je collegeaantekeningen van hoorcolleges en werkgroepen 1 t/m 7 van Experimenteel en Correlationeel Onderzoek, onderdeel van de bachelor Psychologie aan de Universiteit Leiden:
Lecture notes with Experimental and Correlational Research at the Leiden University - 2018/2019
Lecture notes with Experimental and Correlational Research at the Leiden University - 2018/2019
Lecture 1
6/2/2019
-Correlation is about two variables being associated, but there is no evidence of causality.
-Causality however requires multiple factors: covariance (variables have an association), directionality(cause precedes effect (in time)) and internal validity(eliminate alternative explanations).
- Correlations can be displayed in scatterplots that show:
- Direction: positive or negative
- Strength: density of the points
- Shape: linear/nonlinear and homogeneous (one cluster) / heterogeneous (multiple clusters).
- Outliers
-Covariance (sxy): to measure the degree to which two variables vary together.
Formula: sxy = Σ(xi-x)(yi-y) / N-1
It provides us with information on the strength and direction of the association. The disadvantage is that the covariance is dependent on the unit of measurement of the variables.
-Pearson r is a standardized measure that describes the linear relationship between two quantitative variables, and always lies between -1 and +1.
Formulas: r = sxy / sxsy Alternative: r = Σzxzy / N-1
- Remember that a z-score is a standardized score that displays how many standard deviations a certain score is away from the mean.
Alternative correlational techniques:
- The Pearson r is the correlation coefficient that is most commonly used. There are alternatives:
quantitative + quantitative --> Pearson r
ordinal + ordinal --> Spearman’s rho (rs)
dichotomous(only two possible values)+ quantitative --> point-biserial correlation (rpb)
dichotomous + dichotomous --> phi coefficient (ϕ)
-Spearman’s rho (rs) describes relationship between two ordinal variables/ranked scores.
Formulas: xrank = N + 1 / 2 srank = √ (N(N+1) / 2)
rs = r on ranked data
Spearman’s rho is also an alternative to Pearson r in case of outliers and/or weak non-linearity.
-Point-biserial correlation describes relationship between quantitative and dichotomous variables. We use the Pearson correlation formula to calculate rpb: rpb = r
The sign of the correlation (+/-) depends on the way 0 and 1 are assigned to groups.
Relationship rpb and tindependent: rpb = Square root of t2 / t2 + df
-Phi-coefficient (ϕ) describes relationship between two dichotomous variables: ϕ
.....read moreAccess:
JoHo members
Workgroup notes with Experimental & Correlational Statistics at the Leiden University - 2018/2019
Workgroup notes with Experimental & Correlational Statistics at the Leiden University - 2018/2019
Week 1
Prep exercises
- Which combination of measurement levels is required for the use of the Pearson, Spearman, and point-biserial correlation respectively?
- Which formula is suitable for calculating the Pearson, Spearman, and point-biserial correlations?
- Which formula describes the relationship between rpb and tindep?
- Which combination of measurement levels is required for the use of the phi coefficient?
- What is the specific formula for calculating the phi coefficient?
- Which formula describes the relationship between φ and χ2?
- What is the formula for testing the difference between two independent correlation coefficients?
- What is the rule of thumb for effect size r2 and r?
Workgroup tips 1
Correlation is NOT causation. It is an association between variables.
Positive correlation = both increase or decrease
Negative = One increases, the other decreases
Pearson’s r; both variables are at an interval level. Formula: ∑ZxZy/n-1
Spearman rho = two ordinal variables (To avoid outlier influence in Pearson’s r) rs = r Important: RANK IT FIRST, then take the z scores
Point Biserial; one dichotomous and one continuous variable rpb = r
Phi is a nominal variable, that only has two levels each aka dichotomous X2 = r
Dichotomous means that the value can only be one of two things. For instance yes/no, male/female, left/right. It is a nominal variable, but where with a simply nominal variable answers can be red/blue/green/yellow, a dichotomous variable could in this case only be red/blue, for instance.
Basically, all of these correlation have the basic formula, which is ∑ZxZy/n-1
R is about sample, ρ is population
Parameter | Population | Sample |
Mean | µ | x̄ |
Probability | P | p |
Standard Deviation | σ | S |
Correlation |
Access:
JoHo members
Experimenteel en Correlationeel Onderzoek: Samenvattingen, uittreksels, aantekeningen en oefenvragen - UL
Experimenteel en Correlationeel Onderzoek: Samenvattingen, uittreksels, aantekeningen en oefenvragen - UL
- In deze bundel worden o.a. samenvattingen, oefententamens en collegeaantekeningen gedeeld voor het vak Expirimenteel en Correlationeel Onderzoek voor de opleiding Psychologie, jaar 1, aan de Universiteit Leiden
- Engelstalige studiehulp kan je vinden in de bundel bij het vak Experimental and Correlational Research
- Voor een compleet overzicht van de door JoHo aangeboden samenvattingen & studiehulp en de beschikbare geprinte samenvattingen voor dit vak ga je naar de Samenvattingen Startpagina Psychologie Bachelor 1 - UL op WorldSupporter.org
Click & Go to related summaries or chapters
Study guide with lecture notes for Psychology Bachelor 1 at Leiden University
Lecture notes with Psychology Bachelor 1 at Leiden University
Table of content
- Workgroup notes with Personality, Clinical and Health Psychology - 2018/2019
- Workgroup notes with Inferential Statistics - 2018/2019
- Lecture notes with Experimental and Correlational Research - 2018/2019
- Workgroup notes with Experimental and Correlational Research - 2018/2019
- Lecture notes with Social and Organizational Psychology - 2018/2019
- Lecture notes with Developmental and Educational Psychology - 2018/2019
Supporting content:
Access:
Public
Study guide with lecture notes for Experimental and Correlational Research at the Leiden University
Study guide with lecture notes
Lecture notes with Experimental and Correlational Research
- For lecture notes and workgroup notes
- see the supporting content of this study guide
Supporting content:
Access:
Public
Check how to use summaries on WorldSupporter.org
Online access to all summaries, study notes en practice exams
- Check out: Register with JoHo WorldSupporter: starting page (EN)
- Check out: Aanmelden bij JoHo WorldSupporter - startpagina (NL)
Using and finding summaries, study notes en practice exams on JoHo WorldSupporter
There are several ways to navigate the large amount of summaries, study notes en practice exams on JoHo WorldSupporter.
- Starting Pages: for some fields of study and some university curricula editors have created (start) magazines where customised selections of summaries are put together to smoothen navigation. When you have found a magazine of your likings, add that page to your favorites so you can easily go to that starting point directly from your profile during future visits. Below you will find some start magazines per field of study
- Use the menu above every page to go to one of the main starting pages
- Tags & Taxonomy: gives you insight in the amount of summaries that are tagged by authors on specific subjects. This type of navigation can help find summaries that you could have missed when just using the search tools. Tags are organised per field of study and per study institution. Note: not all content is tagged thoroughly, so when this approach doesn't give the results you were looking for, please check the search tool as back up
- Follow authors or (study) organizations: by following individual users, authors and your study organizations you are likely to discover more relevant study materials.
- Search tool : 'quick & dirty'- not very elegant but the fastest way to find a specific summary of a book or study assistance with a specific course or subject. The search tool is also available at the bottom of most pages
Do you want to share your summaries with JoHo WorldSupporter and its visitors?
- Check out: Why and how to add a WorldSupporter contributions
- JoHo members: JoHo WorldSupporter members can share content directly and have access to all content: Join JoHo and become a JoHo member
- Non-members: When you are not a member you do not have full access, but if you want to share your own content with others you can fill out the contact form
Quicklinks to fields of study (main tags and taxonomy terms)
Field of study
- Communication & Media sciences
- Corporate & Organizational Sciences
- Cultural Studies & Humanities
- Economy & Economical sciences
- Education & Pedagogic Sciences
- Health & Medical Sciences
- IT & Exact sciences
- Law & Justice
- Nature & Environmental Sciences
- Psychology & Behavioral Sciences
- Public Administration & Social Sciences
- Science & Research
- Technical Sciences
Exam Tips JulitaBonita contributed on 07-03-2019 11:06
A now 2nd year IBP student, shared her exam tips for this course last year. Check out the relevant content > IBP Leiden-Experimental and Correlational Research. You can also follow Ilona's profile for more summaries, blogs and lecture notes.
Lecture notes Experimental and Correlational Research Psychology Supporter contributed on 28-03-2019 16:37
Also interested in reading the complementary lecture notes for the course this year? Check out Noa's profile for relevant content!
Add new contribution