sampling error think of sampling as benefiting from room for movement

Whats the correlation?

Sampling Errorthink of sampling as benefiting from room for movement

Sampling Errorthink of sampling as benefiting from room for movement

PopulationSampleX_The population mean is . The sample mean is X. _3

PopulationSampleX_The population mean is . The sample mean is X. The population standard deviation is , the sample sd is s._s4

PopulationSampleA XA_SampleB XBSampleE XESampleD XDSampleC XC____In reality, the sample mean is just one of many possible samplemeans drawn from the population, and is rarely equal to .5

PopulationSampleA XA_SampleB XBSampleE XESampleD XDSampleC XC____In reality, the sample mean is just one of many possible samplemeans drawn from the population, and is rarely equal to .sasbscsdse6Sampling error = Statistic - ParameterSampling error for the mean = X - _Sampling error for the standard deviation = s - 7Unbiased and Biased Estimates

An unbiased estimate is one for which the mean samplingerror is 0. An unbiased statistic tends to be neither largernor smaller, on the average, than the parameter it estimates.

The mean X is an unbiased estimate of .

The estimates for the variance s2 and standard deviation shave denominators of N-1 (rather than N) in order to beunbiased._8SSN2=9SS(N - 1)s2=10SS(N - 1)s=11Correlations describe co-variationon two variables.



Whats the correlation?.69



















Rounded, the mean reading score is 52 and sd=10 and the mean math score is also 52 and sd=10. If a given students reading score is 67, then what is your best estimate of her math score? .69

In predicting someones math score, if you could have just one piece of information, and it is either (a) her reading score, or (b) her self concept score, which would you rather have? Whats it worth to you?.69.16

Explain to a non-statistician what it means to say reading and math scores are correlated r=.69 in this population..69A key to understanding rzy = zxWhen X and Y are perfectly correlated37We can say that zx perfectly predicts zy

zy = zx

Or

zy = zx

^38When they are imperfectly correlated, i.e., rxy 1 or -1zy = rxyzxr is the slope of the predicted line, with a zero-intercept of zy=039Explain to a non-statistician what it means to say reading and math scores are correlated r=.69 in this population.

sampling error think of sampling as benefiting from room for movement

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