PSYC 1010 Study Guide - Final Guide: Statistical Parameter, Test Statistic, Standard Deviation
29 Jun 2018
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Department
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1010 exam Chapter 9
The T Distributions
•Tells us how confident we can be that the sample differs from the larger population
•Use when we don't know the population standard deviation
Estimating population Standard Deviation From a Sample
•Estimate the population standard deviation by using the sample standard deviation,
•Step1: Find sample mean
•Step2: Use sample mean in the corrected formula for the standard deviation ,
The Single-Sample T Test
•compares a sample from which we collect data to a population for which we know the mean
but not the standard deviation
•use table
•Don’t look at the actual sample size, but the degree of freedom
•the number of scores that are free to vary when we estimate a population parameter
from a sample
The 6 Steps of The Single-Sample t Test
•Step1: Identify the population, distribution, and assumption
•Step2: State the null and research hypothesis
•Step3: Determine the characteristics of the comparison distribution
•Find mean
•Then use standard deviation formula is the sum of square {∑( X-M)^2}
•Then, After,
•Step4: Determine the critical values or cutoffs
•df= N-1 —> Use 2-tailed test with a p level of 0.05, look up the critical values on df
table
•Step5: Calculate the test statistic
•Step6: Make a decision
Calculating a Condense Int
)1(
)( 2
−
−
=∑
N
MX
s
s=(X−M)2
∑
(N−1)
