Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
48 Cards in this Set
- Front
- Back
|
Descriptive Statistics
|
method for organizing and describing experimental data
|
|
|
Inferential Statistics
|
method for making decisions about the significance of experimental results. were the results caused by the IV or just by chance
|
|
|
cumf
|
the cumulative frequency. the number of scores at or below any given score
|
|
|
cumprop
|
the proportion of scores at or below any given score ( take the cumf and divide by the total number of scores)
|
|
|
%ile
|
percentage of scores at or below any given score
|
|
|
x
|
the data (scores) arranged from lowest to highest
|
|
|
f
|
the frequency with which each score occurs in the data
|
|
|
mean
|
mathematical average of a group of scores, the sum of the scores divided by the number of scores
(most vulnerable to extreme scores) |
|
|
median
|
the middle score, at the 50%ile where 1/2 the scores are above and 1/2 the scores are below(best used for skewed distributions)
|
|
|
range
|
the simplist measure. the difference between the highest and lowest scores in the distribution
|
|
|
Deviation
|
the difference between a given score and the mean of the distribution D=x - xbar
|
|
|
Variance
|
the square of a scores deviation from the mean d2=variance.
|
|
|
standard deviation
|
the avergae deviation of all scores from the mean
|
|
|
calculating standard dev.
|
1. find mean of distributon
2. create freq. dist. chart -x(score) -f(freq.) -d(deviation, the score-mean) -d2(variance, deviation squared) -fd2(variance * freq) 1 add up all the numbers in fd2 2 divide dum of fd2 by N 3 take square root of result |
|
|
Normal frequency distribution
|
symmetrical all around
mean=median=mode |
|
|
Non-Normal
(Skewed Curves) |
skewed to right or left. either few extremly high scores or a few extremly low scores
|
|
|
Non-Normal
(Ogive Curve) |
s-shaped curve. either all high scores or all low scores.
|
|
|
Non-Normal
(Bimodal Curve) |
m-shaped. has two modes.
|
|
|
Non-Normal
(U-shaped Curve) |
U-shaped. extreme scores on both ends.
|
|
|
Normal
(Leptokurtic Curve) |
small standard dev. (scores all bunched up around mean)
|
|
|
Normal
(Platykurtic) |
large standard deviation (scores very spread out)
((very LOOOOONG) |
|
|
Normal
(Mesokurtic) |
classic shape. Standard normal curve.
|
|
|
xbar
+1, +2, +3 numbers |
50%tile
34.13% 13.59% 2.15% .14% |
|
|
percentiles can also be seen as...((13.59%))
|
probabilities ((P=.1359))
|
|
|
z-score defintion
|
allows us to determine the exact distance of any given score from mean (in standard deviations). All you need is the mean and stand. dev.
|
|
|
z-score formula
|
z= (x-xbar)/ standard dev.
|
|
|
example of z-score
IQs=140 xbar= 200 SD=30 IQmj=60 xbar=30 SD=10 |
s=-2
mj=+3 |
|
|
correlation
|
refers to the type and the strength of the relationship between two variables. Correlation data does not indicate a cause and effect relationship.
|
|
|
correlation coefficient
|
Pearson's r
+1=perfect/direct + rel.(Aup B up) 0.00=no relationship -1=perfect/indei2rec/inverse/- relationship (Aup B down) |
|
|
Logic of inferential statistics
|
to decide if the difference between the experimental group mean and the control group mean was caused by the IV or just chance
|
|
|
Null Hypothesis (Ho)
|
Nearly always define the Ho as follows "the difference between the xbar"e" and the xbar"c" is caused due to chance" (Assumption/Theory)
(skepticism) |
|
|
Ho is correct
Fail to reject the Ho |
assert difference is due to chance
|
|
|
Ho is incorrect
Reject the Ho |
assert difference is caused by IV
|
|
|
alpha level
|
the probability of an event occuring by chance at which one is willing to reject the Ho
|
|
|
alpha=.01
|
p=1 of 100 times (by chance)
|
|
|
alpha=.05
|
p= 5 of 100 times (by chance)
|
|
|
if Xbar"e" < alpha...
|
reject Ho
caused by IV |
|
|
if xbar"e" > alpha...
|
fail to reject the Ho
caused by chance |
|
|
diff between descriptive/inferential
|
make decisions with inferential andnot with descriptive. describe with descriptive
|
|
|
if r=+1.00 and variable A is decreasing what is happening to variable b
|
also decreasing
|
|
|
mean is 10. sd is 2. what is score at z=+2
|
14
|
|
|
cumulative freq.
|
number of scores @ or below or @ and above
|
|
|
type 1 error
|
increases as alpha increases=rejecting the ho when it is true=stating IV caused the result when it was really due to chance
|
|
|
type 2 error
|
increases as alpha gets smaller=failing to reject t he Ho when it is really false=stating the result was due to chance when was due to IV
|
|
|
ANOVA
|
stat. use for multiple IV's
|
|
|
students t
(t-test) |
used when control group represents the entire pop.
|
|
|
omega-squared
|
correlation between IV and DV= helps detect interactions between variables
|
|
|
chi-squared
|
compares observed outcomes(data) with expected outcomes (Ho)
|
