Date: Thu, 9 Aug 2001 12:42:42 +0000
ReplyTo: Shail Dobson <dobson_shail@HOTMAIL.COM>
Sender: "SPSSX(r) Discussion" <SPSSXL@LISTSERV.UGA.EDU>
From: Shail Dobson <dobson_shail@HOTMAIL.COM>
Subject: Re: Why ttest?
ContentType: text/plain; format=flowed
Yes, we could always use the ttest for comparing means, irrespective of
sample size.
>From: David Brown <david_brown123@YAHOO.CA>
>ReplyTo: David Brown <david_brown123@YAHOO.CA>
>To: SPSSXL@LISTSERV.UGA.EDU
>Subject: Why ttest?
>Date: Thu, 9 Aug 2001 08:22:50 0400
>
>Hello,
>
>The ttest is used to test the null hypothesis of no
>difference between the means of two independent
>samples. The ttest is suitable for small sample
>sizes; therefore, the tdistribution is used as the
>sampling distribution instead of the normal
>distribution. When the degrees of freedom reach 100+,
>the tdistribution approaches the normal distribution;
>thus, the ttest would act like a ztest. For a sample
>size of 30+, the ztest is used.
>
>My question is why wouldn’t we always use a ttest?
>
>David
>
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