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S.O.C.S?
 Shape: symmetric (normal curve); Skewed Right or Skewed Left
 Outliers: 1.5(IQR). IQR? Q3Q1
 Center: Value that divides the distribution so that half are larger and half are smaller
 Spread: Smallest and largest value

When to use dotplots?
categorical variables.

When to use barcharts?
compare the sizes of categories or groups. Sizes can be measures as frequencies or percentages.

When to use Histograms?
large data sets involving quantitative variables.

When to use Stemplots? what's the difference beween histograms and stemplots?
histograms: show many scores that fall into each group but the exact values are often lost.
Stemplots show these exact values.

What to use for categorical data?
dotplots and bar charts.

What to use for quantitative?
histograms, cumulative frequency plots (ogives) and stemplots.

Steps when looking for a variance:
*see page 60 Barron's*

What's the empirical rule?
689599.7

What happens to the spread after adding the same constant to the mean and median?
stays the same

relationship of the mean and median on...
skewed left
skewed right
 mean is less than the median
 mean is usually greater than the median

make a least square regression line on the calculator. *page 113*
*pg. 113*

what's correlation? *definition*
correlation r is equal to the slope of the regression line when zscores for the yvariable are plotted against zscores for the xvariable.

which are affected by the outliers?
Mean, Standard Deviation, Range

what will cause a greater power of a test?
 larger sample size
 larger alpha

when do you use a significant test?
 when testing a claim.
 ex: ho; ha

what's true about the tdistribution?
 there are different tdistributions for different values of df( degrees of freedom)
 bellshaped and symmetric
 more spread out than the normal distribution
 the larger the df value, the closer the distribution is to the normal distribution

what's systematic sampling?
 list the population in some order
 choose a random point to start
  i.e. picking every 10th, 50th, etc.

What's stratisfied sampling?
 population is divided into homogenous groups called stratas. random samples from each strata are chosen.
 stratify by age, gender, income level etc.

cluser sampling?
 population is divided into heterogenous groups called clusters.
 take a random sample of clusters.

2sample confidence interval Mean

2sample confidence interval Proportions

2sample significance test Mean

2 sample significant test proportion

1sample significant test mean

1 sample significant test proportion

1 sample confidence interval

1 sample confidence interval proportion

you've made a confidence interval and you want to see if there's a difference between the two means. the interval is 1.3692, .0308. is there a difference?
since it does not reach 0, there is evidence that there is a difference between the two means.

