Internal Assessment Review

Data Processing/Statistical Analysis

Data Processing/Statistical Analysis

Calculating Reaction Rates:This is a slope - just like in math class!rate = y = y2-y1

Graphing:At least two ways to graph data:

x x2-x1

Data Processing/Statistical Analysis

Write down a definition for each of the following:MeanRangeStandard DeviationError Bars

Data Processing/Statistical Analysis

Check your work:Mean - average of data pointsRange - spread of data (difference between smallest

and largest point)Standard Deviation - measure of spread of data around

the mean (how tightly clustered the data are)Error Bars - represent variability of graphed data - can

show range or standard deviation

Statistical Analysis

If you are going to use a statistical test, you should state a null hypothesis. What is a null hypothesis?

When would you use a correlation test (Pearson r value)?

When would you use a t-test?

Null Hypotheses

If you are going to use a statistical test, you should state a null hypothesis. What is a null hypothesis?

A null hypothesis predicts no difference between your data sets.

Ex. No correlation exists between dog size and hours

of barking per day.There is no difference in coolness of left-handed

and right-handed people.

CorrelationWhen would you use a correlation test (Pearson r value)? To determine the correlation between two variables.

Shortcuts in Excel: =PEARSON(array 1, array 2)=CORREL(array 1, array 2)

How to interpret:

-1 0 1

Strong No Strong negative correlation positive (Reject null) (Accept null) (Reject null)

quickdemo

Correlation

r2 is the coefficient of determinationHow to interpret:r2 can be reported as a %, and tells you how much of

the variance of one variable is accounted for by the other variable.

Ex. If the correlation between dog size and amount of barking is r=.90 (strong positive correlation, reject null hypothesis), then r2=.81

This means that 81% of the variation in barking can be accounted for by dog size. You could make a good prediction of barking based on size.

t-Test When would you use a t-test?To compare the means of two data sets.

Shortcuts in Excel: = TTEST(array 1, array 2, tails, type)**tails=2, type=2

How to interpret:If p>0.05, Accept the null hypothesis There is no significant difference between data sets.If p<0.05, Reject the null hypothesis There is a significant difference between data sets.

quickdemo

t-Test How to interpret:If p>0.05, Accept the null hypothesis There is no significant difference between data sets.If p<0.05, Reject the null hypothesis There is a significant difference between data sets.

Ex. Null hypothesis: There is no difference in coolness of left-handed vs right-handed people.

If p=0.01...will you accept or reject the null hypothesis?…..is there a significant difference in coolness?

Review <, >

Wiki ResourcesWhat page will you find the “Excel Stats Activity” and

“Statistics Review” on?IA Resources

How might these resources help you with your IA?