Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media...
-
Upload
jayson-isaac-kelly -
Category
Documents
-
view
216 -
download
2
Transcript of Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media...
![Page 1: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/1.jpg)
Last bits of inferential statistics
![Page 2: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/2.jpg)
Check in
• Proposal DRAFT due Tuesday
• Research in media assignment Tuesday
• Quiz Tuesday the 29th
– Will cover statistics material– Multiple choice
![Page 3: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/3.jpg)
Conducting statistical tests
• Testing our hypotheses numerically
• Do the data support the null distribution?
• Do the data support the alternate distribution?
• Tests tell us if the difference in distributions is significantly different– Not just look different, but different enough so
we are pretty sure its not an accident
![Page 4: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/4.jpg)
Some basic tests
• Remember there are many different types of distributions
• The normal distribution and others
• Tests are often named for their distributions
![Page 5: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/5.jpg)
Tests—first look
• Chi-Squared– The X2 distribution
• T-test– The students T distribution
• Rho– The correlation coefficient R– Assumes a normal distribution or T
distribution
![Page 6: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/6.jpg)
How to choose which test?
• Many tests may answer the same type of question
• Which test you use depends on your questions and variables
• Are your variables continuous or categorical?
• May also matter if independent variable is one type, and dependent variable is another type
![Page 7: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/7.jpg)
What type of variable do I have
• Independent variable– The predictor– E.g. If I believe that gender predicts income,
then gender is the IV
• Dependent variable– The outcome– E.g. if I believe that anxiety predicts eating
habits, then eating habits is the DV
![Page 8: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/8.jpg)
What type of variable do I have?
• Not all questions have an independent and dependent variable
• If I’m asking if two things are ASSOCIATED or CORRELATED there is no actual IV or DV
• A variable may be an IV in one question and a DV in another question, and vice versa
• It depends on my question
![Page 9: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/9.jpg)
Continuous vs. categorical?
• Continuous– May actually be based on ordinal– When I have a large range of numerical
ratings– Height, weight– Symptoms, feelings
![Page 10: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/10.jpg)
Continuous vs. categorical
• Categorical– May have levels– Has few categories– 1,2,3– Yes/no– Red/blue
![Page 11: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/11.jpg)
Which test?
• If my question is– Are these two groups different?
• And my outcome is – Categorical
• I use a X2 test
![Page 12: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/12.jpg)
Differences between 2 groups
• IV is 2 groups– E.g. men and women– Catholics and Protestants– People who have a peanut allergy and people
who don’t
• So I know that the IV is categorical
![Page 13: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/13.jpg)
Differences between 2 groups
• If DV is also categorical
• Will also be a sort of “grouped” variable– Employed/unemployed– Married/not married– College degree/no college degree
![Page 14: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/14.jpg)
Chi Squared Test
• If our predictor is categorical
• And our outcome is categorical
• Then we use a chi-squared test– A “2 x 2 table approach”
![Page 15: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/15.jpg)
Example
• Does gender predict employment– Gender is categorical– Employment is categorical– This is a chi-squared test
• Tells us if there is a difference in the expected rate of occurrence, and the observed rate of occurrence
![Page 16: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/16.jpg)
Example
• Assume gender is 50/50• If gender does NOT predict employment,
then we expect equal numbers of men and women to be employed
• If gender DOES predict employment we observe unequal numbers of men and women employed
• Chi square tests if observed and expected are significantly different
![Page 17: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/17.jpg)
Which test?
• If my question is are these 2 groups different
• And my outcome is continuous
• I use a T-test
![Page 18: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/18.jpg)
T-tests
• Also a test of difference between groups
• When the IV is categorical
• And the DV is continuous
• E.g. IV—men/women
• DV—height in inches
![Page 19: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/19.jpg)
T-tests-examples
• IV—Dogs/Cats
• DV—weight in pounds and ounces
• IV—employed/unemployed
• DV—income in dollars
• IV—full time student/not full time
• DV—average hours of sleep per night
![Page 20: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/20.jpg)
Which test?
• If my question is are these characteristics related or unrelated
• I am looking at the relation between two continuous variables
• I use a correlation test
![Page 21: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/21.jpg)
Correlation
• Not a test of differences between groups
• A test of whether two continuous variables are related or unrelated
• The statistic is R
![Page 22: Last bits of inferential statistics. Check in Proposal DRAFT due Tuesday Research in media assignment Tuesday Quiz Tuesday the 29 th –Will cover statistics.](https://reader035.fdocuments.us/reader035/viewer/2022062515/56649f4e5503460f94c7011a/html5/thumbnails/22.jpg)
Examples
• Height and Weight
• Grade point average and hours of study
• Hours of sleep and scale measure of exhaustion