Transcript Intro to quantitative methods in sociology

Intro to quantitative
methods in sociology
Statistics
a collection of methods for planning
experiments, obtaining data, and then
organizing, summarizing, presenting,
analyzing, interpreting, and drawing
conclusions based on the data.
Population
the complete collection of all
elements (scores, people,
measurements, and so on) to be
studied. The collection is complete
in the sense that it includes all
subjects to be studied.
Census
the collection of data from every
member of the population.
Sample
a sub-collection of elements
drawn from a population.
Sampling
► In
order to properly understand statistics when
they are presented to you, you must understand
how the study “population” was defined and
sampled for
► There are many sampling designs, some superior
to others
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Snowball
Convenience
Random
Stratified random clusters
Operationalizing variables
► Many
things that sociologists wish to study are
difficult to observe (class, race, sometimes gender,
as well as things like cohesiveness and conflict)
and require a “working definition”
► Sociologists employ variables or parameters that,
while frequently not being the actual concept to
be measured, are thought to capture the
phenomenon in question
 Social Class example
What you can glean from these
analyses
► Gives
information on a broad spectrum of
people
► The information is a bit rough, however
► Most useful for determining how often and
to whom something is happening
 Compare to qualitative modes of inquiry where
the how and why are answered
Where it all goes wrong
► Bad
samples producing bad data
 Garbage in, garbage out
► Erroneous
statistical assumptions
► Poor operationalizing of variables
► Misinterpretation of statistics
Misuses of Statistics
► Voluntary
response sample (self-selected)
Internet, call-in, magazine polls
► Small samples
“4 out of 5 dentists prefer…”
► Self-Interest Study
Company-sponsored studies
► Precise Numbers
“People spent an average of $23.12 on a gift”
 Voluntary
response sample
(or self-selected survey)
one in which the respondents themselves decide whether to
be included.
In this case, valid conclusions can be made only about the
specific group of people who agree to participate.
 When America Online runs a poll on the internet, individuals decide
themselves whether to participate, so they constitute a voluntary
response sample. People with strong opinions are more likely to
participate, so the responses are not representative of the whole
population.
 Mail- in polls, where subjects can decide whether to reply.
 Telephone call- in polls, where newspaper, radio, or TV
announcements ask that you pick up a phone and call a number.
Questions
► Loaded
questions
► Order of questions
► Refusals (non-response)
Misleading Graphs
Salaries are Going Up!
Monthly Salary ($)
Monthly Salary ($)
Salaries Barely
Increased
3000
2500
2000
1500
1000
500
0
1994
2004
Year
2350
2300
2250
2200
2150
2100
2050
2000
1994
2004
Year
Misleading Pictographs
Worker Salary
$2000/mo
Manager Salary
$4000/mo
Percentages
has to be of something
► 100% means all of it
► Percents are based on a “base” amount
10% extra savings on clearance
merchandise (50% off).
$100 coat -> $50 clearance price
10% extra -> $45 final, not $40
► Percentage
Correlation and Causation
► Just
because two things have a relationship does
NOT mean one causes the other.
► Even when a causal relationship is likely, we have
to be careful about assuming what is the cause,
and what is the effect.
Golf scores and salary for CEOs
Prozac and Suicide risk