Ch. 2 Research Methods

Double Blind vs. Single Blind

Double Blind vs. Single Blind Single Blind- only researcher knows who is experimental and who is control group. Double Blind- both the researcher and the participant don’t know who is in the experimental group and whose in the control group.

Ethics!

How to get my project approved Go through the International Review Board to insure all ethical guidelines are met.

6 Ethical principles: 1. Protection from Harm: make sure participants can no way be harmed. 2. Debriefing: at the end, make sure particiapants are told about nature of the event and that it was just a trial. Make sure participants are returned to state before trial. 3. Privacy: make sure participants to know the results of their trial will be completely private. 4. Informed Consent: make sure participants say, yes I am willing to partake in study. 5. Deception: make sure participants are not by any way lied to or deceived in order to change the results. 6. Right to Withdrawal: make sure participants know they have the right to withdrawal from a study at any time.

Psychological Statistics Yay Math!

Wait there is math in psychology? And you thought Psychology was a science.

Measures of central tendancy Mean- The average Median- the number ranked in the middle of distribution Mode- the number that occurs the most in a set Why is average not always the best go-to stat when understanding your data?

Variables Independent- The variable being manipulated by the researcher. Dependent- the variable that is the outcome of the independent variable. Or the lack thereof. Cofound- the variable the makes a study invalid.

Confound Example Madison Central is experimenting to see how well an hour of class outside effects student motivation. Thus next year MCHS will offer an English 12 class outside during 1st, 4th, and 6th periods. What is the ID, DV, and Confound V?

Correlation Correlations can be: Strong, weak, positive, negative, or none

How to understand Correlations If the stairs are building up from point (0,0) , it is positive. If the points are moving down from point (0,0) then its negative The closer the points are, the stronger the correlation is

Correlation relationships A perfect positive relationship would be a +1.0 A perfect negative relationship would be a -1.0 A score of zero would show no relationship. The closer a relation is to 1 or -1 the stronger the relation is. Which would show a higher relation -.75 or .57?

Correlation practice Practice in your notes, write a + if you think there is a positive correlation (meaning both variables move up) a – if both variables move down or a zero if there is no correlation.

Correlation does not mean causation

Standard deviation How to find Standard Deviation? We are going to cheat and use excel. So when we do our research projects. You find standard deviation by entering =STDEV(start of data set: end of data set).

So 1 standard deviation is around 68% of the total population So 1 standard deviation is around 68% of the total population. 2 Standard Deviations are about 95% of the scores, the third standard deviation covers the outlier 5%. Making this easy, if this normal curve represented grades, it would ideally show that 68% of the grades fell within (whatever the standard deviation was )of a 75 % mid C.

Math practice problem We surveyed a neighborhood of families to see how often they visited fast-food restaurants within a 6 month window and here were our results. 30, 50, 30, 40, 34, 89, 54, 89, 45, 23, 56, 43, 23, 45 Calculate the mean And then the Standard deviation! (evil laugh, jk I’ll do that one for you)

Mean- 46.5 SD- 10.6066 Meaning that 68% of the families in the neighborhood we surveyed visited a fast food restaurant in between 35.9 times and 57.1 times (roughly)

What does this tell us Sometimes the measures of central tendency don’t give us the information needed to understand if data is reliable, ideally you would like to have you standard deviation smaller so that all of your range is a lot closer. During a test if the class average is a 75 I would rather have a SD of 5 than 15. If 68% of the class scored between a 70-80 then it would show that test was a lot more reliable. If 68% of the class scored between a 90 and 60 then the it would show that the test wasn’t quite as reliable, or that the class has a wide range of good and bad test takers.