All notes from the hearing lectures and practical units, SPSS explanation - Part of the bachelor and/or premaster of Communication and information sciences / communicatie- en informatiewetenschappen at Tilburg University
Ps: Passed statistics with a 9. Good Luck!
Reporting results:
Wrong: “The higher you score on age, the higher you score on hours watching TV”
Right: “People who are older watch significantly more TV than people who are younger”
Right: “The older people are, the more time they spend watching TV”
The research process:
Generating theories and hypotheses:
Theories: An hypothesized general principle set of principles that explain known findings
about a topic from which new hypotheses can be generated (e.g. Newton’s new law of
universal gravitation).
Hypothesis: a prediction (scientific statement) from a theory
Testing hypotheses through falsification:
You can only examine whether a theory/hypothesis is credible, if there is a possibility to
disproof it.
The principle of hypothesis testing:
Point of departure / H0: assumption that there is no difference
- This gives a point of comparison
- If no difference then V1 – V2 = 0
- We can predetermine: If I measure e.g. IQ in 1000 persons, and the mean
difference between men and women is larger than 5 IQ-points, then it is very
unlikely that this difference is coincidence.
Types of hypotheses:
,Null hypothesis, H0:
This is the one we try to reject
There is no effect (most of the time)
E.g.: “Women are equally likely as men to wear a skirt or dress OR there is no
relationship between age and the number of wrinkles you have.
The alternative hypothesis, H1:
if we can reject H0, this one us supported by the data, but not proven!
E.g. Woman are more likely to wear a skirt or dress than men OR There is a positive
relationship between age and the number of wrinkles you have: the older people are,
the more wrinkles they have.
HC2:
, Make a histogram: graphs, chart builder, drag histogram to white box, run syntax. Shoesize is
for example not normally distributed, because you are including both genders (bimodal = 2
peaks). When you would separate the gender it would be more normally distributed.
When we measure a phenomenon in real life, there is usually variation in how the
phenomenon presents itself noticeable in the frequency distribution
Frequency distributions (aka histograms):
A graph plotting values of observations on the horizontal axis, with a bar showing how many
times each value occurred in the data set.
The normal distribution:
- bell shaped
- symmetrical around the centre
- the curve shows the idealized shape
we assume that a lot of characteristics are distributed normally in the entire population
Kurtosis: about the heaviness of the tails
more spiky (positive) = leptokurtic,
more bulky (negative) = platykurtic.
Still symmetrical
Skewness: about the symmetry of the distribution (not symmetrical anymore)3
Positive skew: scores bunched at low values with the tail pointing to high values; or tail-to-
right
Negative skew: scores bunched at high values with the tail pointing to low values; or tail-to-
left
Problem visualizing data in a histogram is informative, but can we find a more concise
representation of our data? And is there a way to predict someone’s score (more or less
accurately)
important features of a distribution:
The centre:
- mode: what happens most, good when you talk about categorical data
Issues with the mode: not necessarily informative, especially not in cases that
are not symmetrical
Bimodal: having to modes
Multimodal: having several modes
-median: the middle score when scores are ordered
Not so sensitive to outliers
But not always representative
- mean: the sum of scores divided by the number of scores.
The mean is a model of what happens in the real world: the typical
score. It’s not a perfect representation of the data.
Problem: really sensitive to outliers
How can we assess how well the mean represents reality?
The dispersion: (variation in data)
- range: the smallest score subtracted from the largest
But, very biased by outliers, and not so representative
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
Verzekerd van kwaliteit door reviews
Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!
Snel en makkelijk kopen
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
Focus op de essentie
Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper kellyvanhelvoirt1. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €4,49. Je zit daarna nergens aan vast.
